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If not, see . + +Also add information on how to contact you by electronic and paper mail. + + If the program does terminal interaction, make it output a short +notice like this when it starts in an interactive mode: + + Copyright (C) + This program comes with ABSOLUTELY NO WARRANTY; for details type `show w'. + This is free software, and you are welcome to redistribute it + under certain conditions; type `show c' for details. + +The hypothetical commands `show w' and `show c' should show the appropriate +parts of the General Public License. Of course, your program's commands +might be different; for a GUI interface, you would use an "about box". + + You should also get your employer (if you work as a programmer) or school, +if any, to sign a "copyright disclaimer" for the program, if necessary. +For more information on this, and how to apply and follow the GNU GPL, see +. + + The GNU General Public License does not permit incorporating your program +into proprietary programs. If your program is a subroutine library, you +may consider it more useful to permit linking proprietary applications with +the library. If this is what you want to do, use the GNU Lesser General +Public License instead of this License. But first, please read +. diff --git a/Makefile_many b/Makefile_many index 19a525a..966a297 100644 --- a/Makefile_many +++ b/Makefile_many @@ -5,7 +5,7 @@ # C/CPP # Don't use the standard names like `CC` and `CXX` to avoid `?=` getting overridden. # by the Makefile default values. -ALL_DEPEND ?= +ALL_DEPEND ?= MYCC ?= gcc MYCXX ?= g++ G ?= gdb3 diff --git a/c-from-cpp/Makefile b/c-from-cpp/Makefile index 744262a..2d528dd 100644 --- a/c-from-cpp/Makefile +++ b/c-from-cpp/Makefile @@ -5,10 +5,10 @@ main.out: main.o c.o g++ -o '$@' $^ c.o: c.c - gcc -c -o '$@' -std=c89 -Wextra -pedantic-errors '$<' + gcc -c -g -o '$@' -std=c89 -Wall -Wextra -pedantic-errors '$<' main.o: main.cpp - g++ -c -o '$@' -std=c++98 -Wextra -pedantic-errors '$<' + g++ -c -g -o '$@' -std=c++98 -Wall -Wextra -pedantic-errors '$<' run: main.out ./main.out diff --git a/c-from-cpp/README.md b/c-from-cpp/README.md index 466229a..d6f1448 100644 --- a/c-from-cpp/README.md +++ b/c-from-cpp/README.md @@ -1,20 +1,3 @@ # C from C++ -How to call C code from C++. - -I urge you to use `readelf -s` on the object files to see what they contain. - -Note that the symbols defined by the C++ compiler (thus when using `g++` instead of `gcc`) are much more complicated than those generated by the C compiler. - -This is probably the case because C++ has features like templates and classes, so it must add prefixes and suffixes in an specific manner to make the symbols unique. - -Therefore, it is much easier to call `c` from `c++` (with a C++ compiler) rather than call `c++` from `c` (with a C compiler). Of course, this is because `c++` was made to be backwards compatible with `c`. - -See how `g++` links by default to the `c` standard libraries (for backwards compatibility) since you can simply call functions like `printf` without linking. - -## extern "C" - -`g++` compiles: - -- defined functions to use plain C names in the objects instead of the mangled ones -- undefined declared functions to depend on the C name instead of the mangled one + diff --git a/c-from-cpp/c.h b/c-from-cpp/c.h index 17beebe..f8a5287 100644 --- a/c-from-cpp/c.h +++ b/c-from-cpp/c.h @@ -1,9 +1,8 @@ #ifndef C_H #define C_H +/* This ifdef allows the header to be used from both C and C++. */ #ifdef __cplusplus -// This is required otherwise he C++ includer will look -// for the undefined mangled name. extern "C" { #endif int f(); diff --git a/c-from-cpp/main.cpp b/c-from-cpp/main.cpp index 6cc3627..26dc7e6 100644 --- a/c-from-cpp/main.cpp +++ b/c-from-cpp/main.cpp @@ -4,5 +4,4 @@ int main() { assert(f() == 1); - return 0; } diff --git a/c/interactive/audio_gen.c b/c/interactive/audio_gen.c index 2de63dc..f92ea51 100644 --- a/c/interactive/audio_gen.c +++ b/c/interactive/audio_gen.c @@ -32,7 +32,7 @@ double PI2; void write_ampl(FILE *f, point_type ampl) { uint8_t bytes[2]; bytes[0] = ampl >> 8; - bytes[1] = ampl & 8; + bytes[1] = ampl & 0xFF; fwrite(bytes, 2, sizeof(uint8_t), f); } diff --git a/c/string_to_int.c b/c/string_to_int.c index 7f11ecc..b176e30 100644 --- a/c/string_to_int.c +++ b/c/string_to_int.c @@ -1,6 +1,4 @@ -/* -http://stackoverflow.com/questions/7021725/converting-string-to-integer-c/12923949#12923949 -*/ +/* http://stackoverflow.com/questions/7021725/converting-string-to-integer-c/12923949#12923949 */ #include #include @@ -16,26 +14,25 @@ typedef enum { STR2INT_INCONVERTIBLE } str2int_errno; -/* -Convert string s to int out. - -@param[out] out The converted int. Cannot be NULL. - -@param[in] s Input string to be converted. - - The format is the same as strtol, - except that the following are inconvertible: - - - empty string - - leading whitespace - - any trailing characters that are not part of the number - - Cannot be NULL. - -@param[in] base Base to interpret string in. Same range as strtol (2 to 36). - -@return Indicates if the operation succeeded, or why it failed. -*/ +/* Convert string s to int out. + * + * @param[out] out The converted int. Cannot be NULL. + * + * @param[in] s Input string to be converted. + * + * The format is the same as strtol, + * except that the following are inconvertible: + * + * - empty string + * - leading whitespace + * - any trailing characters that are not part of the number + * + * Cannot be NULL. + * + * @param[in] base Base to interpret string in. Same range as strtol (2 to 36). + * + * @return Indicates if the operation succeeded, or why it failed. + */ str2int_errno str2int(int *out, char *s, int base) { char *end; if (s[0] == '\0' || isspace(s[0])) @@ -92,12 +89,11 @@ int main(void) { assert(str2int(&i, "a10", 10) == STR2INT_INCONVERTIBLE); assert(str2int(&i, "10a", 10) == STR2INT_INCONVERTIBLE); - /* - int overflow. - - `if` needed to avoid undefined behaviour - on `INT_MAX + 1` if INT_MAX == LONG_MAX. - */ + /* int overflow. + * + * `if` needed to avoid undefined behaviour + * on `INT_MAX + 1` if INT_MAX == LONG_MAX. + */ if (INT_MAX < LONG_MAX) { sprintf(s, "%ld", (long int)INT_MAX + 1L); assert(str2int(&i, s, 10) == STR2INT_OVERFLOW); diff --git a/cpp-from-c/Makefile b/cpp-from-c/Makefile index 9ef5bd5..49af79a 100644 --- a/cpp-from-c/Makefile +++ b/cpp-from-c/Makefile @@ -5,10 +5,10 @@ main.out: main.o cpp.o g++ -o '$@' $^ cpp.o: cpp.cpp - g++ -c -o '$@' -pedantic-errors -std=c++98 -Wextra '$<' + g++ -c -g -o '$@' -pedantic-errors -std=c++98 -Wall -Wextra '$<' main.o: main.c - gcc -c -o '$@' -pedantic-errors -std=c89 -Wextra '$<' + gcc -c -g -o '$@' -pedantic-errors -std=c89 -Wall -Wextra '$<' run: main.out ./main.out diff --git a/cpp-from-c/README.md b/cpp-from-c/README.md index 9f90e1f..205e7eb 100644 --- a/cpp-from-c/README.md +++ b/cpp-from-c/README.md @@ -1,13 +1,3 @@ -# C from C++ +# C++ from C -How to call C code from C++. - -I urge you to use `readelf -s` on the object files to see what they contain. - -Note that the symbols defined by the C++ compiler (thus when using `g++` instead of `gcc`) are much more complicated than those generated by the C compiler. - -This is probably the case because C++ has features like templates and classes, so it must add prefixes and suffixes in an specific manner to make the symbols unique. - -Therefore, it is much easier to call `c` from `c++` (with a C++ compiler) rather than call `c++` from `c` (with a C compiler). Of course, this is because `c++` was made to be backwards compatible with `c`. - -See how `g++` links by default to the `c` standard libraries (for backwards compatibility) since you can simply call functions like `printf` without linking. + diff --git a/cpp-from-c/cpp.cpp b/cpp-from-c/cpp.cpp index f425489..fded4e0 100644 --- a/cpp-from-c/cpp.cpp +++ b/cpp-from-c/cpp.cpp @@ -1,9 +1,17 @@ #include "cpp.h" -int f() { - return 1; +int f(int i) { + return i + 1; } -class C { - static int f() { return 1; } -}; +int f(float i) { + return i + 2; +} + +int f_int(int i) { + return f(i); +} + +int f_float(float i) { + return f(i); +} diff --git a/cpp-from-c/cpp.h b/cpp-from-c/cpp.h index 90c449c..2ab77b4 100644 --- a/cpp-from-c/cpp.h +++ b/cpp-from-c/cpp.h @@ -2,11 +2,13 @@ #define CPP_H #ifdef __cplusplus -// This is required otherwise C++ will compile to mangled names, -// and the C includer will not find them. +// C cannot see these overloaded prototypes, or else it would get confused. +int f(int i); +int f(float i); extern "C" { #endif - int f(); +int f_int(int i); +int f_float(float i); #ifdef __cplusplus } #endif diff --git a/cpp-from-c/main.c b/cpp-from-c/main.c index b1b41ac..8f0fd0f 100644 --- a/cpp-from-c/main.c +++ b/cpp-from-c/main.c @@ -2,8 +2,8 @@ #include "cpp.h" -int main() { - assert(f() == 1); - assert(f() == 1); +int main(void) { + assert(f_int(1) == 2); + assert(f_float(1.0) == 3); return 0; } diff --git a/cpp/README.md b/cpp/README.md index 2fe0179..1aca54c 100644 --- a/cpp/README.md +++ b/cpp/README.md @@ -82,6 +82,7 @@ 1. [atomic](atomic_bool.cpp.off) 1. [mutex](mutex.cpp) 1. [algorithm](algorithm.cpp) + 1. [heap](heap.cpp) 1. [functional](functional.cpp) 1. [iterator](iterator.cpp) 1. [limits](limits.cpp) @@ -92,8 +93,13 @@ 1. [tuple](tuple.cpp) 1. Smart pointers 1. [unique_ptr](unique_ptr.cpp) - 1. [random](random.cpp) 1. [Interactive](interactive/) + 1. [bst_vs_heap](interactive/bst_vs_heap.cpp) + 1. [chrono](interactive/chrono.cpp) + 1. [random](interactive/random.cpp) + 1. thread + 1. [sleep_for](interactive/sleep_for.cpp) + 1. [thread_count](interactive/thread_count.cpp) 1. Applications 1. [Design patterns](design_patterns.cpp) diff --git a/cpp/algorithm.cpp b/cpp/algorithm.cpp index b4a94b4..fdc3957 100644 --- a/cpp/algorithm.cpp +++ b/cpp/algorithm.cpp @@ -1,7 +1,3 @@ -/* -# algorithm -*/ - #include "common.hpp" int main() { @@ -25,22 +21,21 @@ int main() { assert((v == std::vector{1, 0, 2})); } - /* - # swap - - Does things equivalent to: - - template void swap (T& a, T& b) - { - T c(a); a=b; b=c; - } - - However stdlib can specialize it to do operations more efficiently. - - Some stdlib classes implement swap as a method. - - Particularly important because of the copy and swap idiom. - */ + /* # swap + * + * Does things equivalent to: + * + * template void swap (T& a, T& b) + * { + * T c(a); a=b; b=c; + * } + * + * However stdlib can specialize it to do operations more efficiently. + * + * Some stdlib classes implement swap as a method. + * + * Particularly important because of the copy and swap idiom. + */ // # randomize { @@ -56,24 +51,22 @@ int main() { assert(v2 == std::vector({3, 2, 0, 1, 3})); } - /* - # equal - - Compares ranges of two containers. - */ + /* # equal + * + * Compares ranges of two containers. + */ { std::vector v {0, 1, 2 }; std::vector v2{ 1, 2, 3}; assert(std::equal(v.begin() + 1, v.end(), v2.begin())); } - /* - # accumulate - - Sum over range with operator+ - - Also has functional versions http://www.cplusplus.com/reference/numeric/accumulate/ - */ + /* # accumulate + * + * Sum over range with operator+ + * + * Also has functional versions http://www.cplusplus.com/reference/numeric/accumulate/ + */ { { std::vector v{2, 0, 1}; @@ -89,11 +82,10 @@ int main() { } } - /* - # find - - Return iterator to first found element. - */ + /* # find + * + * Return iterator to first found element. + */ { std::vector v{2,0,1}; unsigned int pos; @@ -111,29 +103,27 @@ int main() { assert(pos == v.size()); } - /* - # find_if - - Like find, but using an arbitrary condition on each element instead of equality. - - Consider usage with C++11 lambdas and functional. - */ + /* # find_if + * + * Like find, but using an arbitrary condition on each element instead of equality. + * + * Consider usage with C++11 lambdas and functional. + */ { std::vector v{2, 0, 1}; assert(std::find_if (v.begin(), v.end(), odd) == --v.end()); } - /* - # binary_search - - Container must be already sorted. - - Log complexity. - - Only states if the element is present or not, but does not get its position. - - If you want to get the position of those items, use `equal_range`, `lower_bound` or `upper_bound`. - */ + /* # binary_search + * + * Container must be already sorted. + * + * Log complexity. + * + * Only states if the element is present or not, but does not get its position. + * + * If you want to get the position of those items, use `equal_range`, `lower_bound` or `upper_bound`. + */ { std::vector v{0, 1, 2}; @@ -142,37 +132,34 @@ int main() { assert(std::binary_search(v.begin(), v.end() - 1, 2) == false); } - /* - # lower_bound - - Finds first element in container which is not less than val. - */ + /* # lower_bound + * + * Finds first element in container which is not less than val. + */ { std::vector v{0, 2, 3}; auto it = std::lower_bound(v.begin(), v.end(), 1); assert(it - v.begin() == 1); } - /* - # upper_bound - - Finds first element in container is greater than val. - */ + /* # upper_bound + * + * Finds first element in container is greater than val. + */ { std::vector v{0, 1, 2}; auto it = std::upper_bound(v.begin(), v.end(), 1); assert(it - v.begin() == 2); } - /* - # equal_range - - Finds first and last location of a value iniside a ranged container. - - Return values are the same as lower_bound and upper_bound. - - log complexity. - */ + /* # equal_range + * + * Finds first and last location of a value iniside a ranged container. + * + * Return values are the same as lower_bound and upper_bound. + * + * log complexity. + */ { std::vector v{0, 1, 1, 2}; std::vector::iterator begin, end; @@ -197,20 +184,19 @@ int main() { assert(*std::min_element(v.begin(), v.end()) == 0); } - /* - # advance - - Advance iterator by given number. - - If random access, simply adds + N. - - Else, calls `++` N times. - - Advantage over `+`: only random access containers support `+`, - but this works for any container, allowing one to write more general code. - - Beware however that this operation will be slow for non random access containers. - */ + /* # advance + * + * Advance iterator by given number. + * + * If random access, simply adds + N. + * + * Else, calls `++` N times. + * + * Advantage over `+`: only random access containers support `+`, + * but this works for any container, allowing one to write more general code. + * + * Beware however that this operation will be slow for non random access containers. + */ { std::vector v{0, 1, 2}; auto it = v.begin(); @@ -219,11 +205,10 @@ int main() { } #if __cplusplus >= 201103L - /* - # next - - Same as advance, but returns a new iterator instead of modifying the old one. - */ + /* # next + * + * Same as advance, but returns a new iterator instead of modifying the old one. + */ { std::vector v{0, 1, 2}; auto it(v.begin()); @@ -232,125 +217,4 @@ int main() { assert(*itNext == 2); } #endif - - /* - # priority queue - - Offers `O(1)` access to the smalles element. - - Other operatoins vary between `O(n)` and `O(1). - - Most common implementaions are via: - - - binary heap - - fibonacci heap - - Boost offers explicit heap types: fibonacci, binary and others. - - But no guarantees are made. - - As of C++11, does not support the increase key operation. - - A binary heap without increase key can be implemented via the heap function family under algorithm. - */ - - /* - # heap - - Binary heap implementation. - - - - In short: - - - getting largest element is O(1) - - removing the largest element is O(lg) for all implementation - - other operations (insertion) may be O(1) or O(lg) depending on the implementation. - - this makes for a good priority queue. - Exact heap type is not guaranteed. As of 2013, it seems that most implementations use binary heaps. - - For specific heaps such as Fibonacci, consider [Boost](http://www.boost.org/doc/libs/1_49_0/doc/html/heap.html). - - - - There is no concrete heap data structure in C++: - only heap operations over random access data structures. - This is why this is under algoritms and is not a data structure of its own. - - There is however a `priority_queue` stdlib container. - - Why random access structure is needed: - */ - { - int myints[]{10, 20, 30, 5, 15}; - std::vector v(myints, myints + 5); - - /* - # make_heap - - Make random access data structure into a heap. - - This changes the element order so that the range has heap properties - - Worst case time: $O(n)$. - */ - std::make_heap(v.begin(), v.end()); - assert(v.front() == 30); - - /* - # pop_heap - - Remove the largest element from the heap. - - That element is moved to the end of the data structure, but since the - heap should have its length reduced by one, that element will then be out of the heap. - - Assumes that the input range is already a heap (made with `make_heap` for example). - */ - std::pop_heap(v.begin(), v.end()); - - //the element still exists on the data structure - assert(v.back() == 30); - - //the second largest element hat become the largets - assert(v.front() == 20); - - //remove the element from the data structure definitively - v.pop_back(); - - /* - # push_heap - - Insert element into a heap. - - Assumes that: - - - the range 0 - (end - 1) was already a heap - - the new element to be inserted into that heap is at end. - */ - - //add the new element to the data structure - v.push_back(99); - - //reorganize the data so that the last element will be placed in the heap - std::push_heap(v.begin(), v.end()); - - assert(v.front() == 99); - - /* - # sort_heap - - Assumes that the input range is a heap, and sorts it in increasing order. - - The assumption that we have a heap allows for $O(ln)$ sorting, - much faster than the optimal bound $O(n log n)$. - - This is exactly what the heapsort alrotithm does: make_heap and then sort_heap. - */ - - std::sort_heap(v.begin(), v.end()); - //assert(v) - //v == 5 10 15 20 99 - } } diff --git a/cpp/common.hpp b/cpp/common.hpp index 72bbe64..8405996 100644 --- a/cpp/common.hpp +++ b/cpp/common.hpp @@ -28,6 +28,7 @@ #include #include // partial sums, differences on std::vectors of numbers #include // ostream +#include // priority_queue #include // ratio, nano #include #include // multiset, set diff --git a/cpp/heap.cpp b/cpp/heap.cpp new file mode 100644 index 0000000..716cd9f --- /dev/null +++ b/cpp/heap.cpp @@ -0,0 +1,137 @@ +/* First learn how binary heaps work, and how they can efficiently implement + * Dijkstra more efficiently than BST: + * https://stackoverflow.com/questions/6147242/heap-vs-binary-search-tree-bst/29548834#29548834 + * + * There are two ways to make priority queues in C++: + * + * - `make_heap` and other functions in the family, which implement a heap + * on top of a random access container, typically std::vector. + * + * - `priority_queue` class, which seems to just use `std::vector` + `make_heap` by default + * internally: https://stackoverflow.com/questions/11266360/when-should-i-use-make-heap-vs-priority-queue + */ + +#include "common.hpp" + +int main() { + int myints[]{10, 20, 30, 5, 15}; + std::vector v(myints, myints + 5); + + // Heap functions. + { + /* # make_heap + * + * Make random access data structure into a heap. + */ + { + std::make_heap(v.begin(), v.end()); + assert(v.front() == 30); + } + + /* # pop_heap + * + * Remove the largest element from the heap. + * + * That element is moved to the end of the data structure, but since the + * heap should have its length reduced by one, the element is effectively removed. + * + * Assumes that the input range is already a heap, made with `make_heap` for example. + */ + { + std::pop_heap(v.begin(), v.end()); + + // The element still exists on the data structure. + assert(v.back() == 30); + + // The second largest element hat become the largest. + assert(v.front() == 20); + + // Remove the element from the data structure definitively + v.pop_back(); + } + + /* # push_heap + * + * Insert element into a heap. + * + * Assumes that: + * + * - the range 0 - (end - 1) was already a heap + * - the new element to be inserted into that heap is at end. + */ + { + // Add the new element to the data structure. + v.push_back(99); + + // Reorganize the data so that the last element will be placed in the heap. + std::push_heap(v.begin(), v.end()); + + assert(v.front() == 99); + } + + /* # sort_heap + * + * Assumes that the input range is a heap, and sorts it in increasing order. + * + * The assumption that we have a heap allows for $O(ln)$ sorting, + * much faster than the optimal bound $O(n log n)$. + * + * This is exactly what the heapsort algorithm does: make_heap and then sort_heap. + */ + { + std::sort_heap(v.begin(), v.end()); + //assert(v) + //v == 5 10 15 20 99 + } + } + + /* # priority_queue + * + * It could however use some other implementation in theory, and it does seem that GCC libstdc++ does provide + * a few alternatives with the policy base + * + * No Fibonacci as of 7.3.0 however: + * + * - https://gcc.gnu.org/onlinedocs/gcc-7.3.0/libstdc++/manual/manual/policy_based_data_structures_test.html#performance.priority_queue + * - http://stackoverflow.com/questions/14118367/stl-for-fibonacci-heap + * + * TODO As of C++11, does not support the increase key operation. + * + * Boost offers explicit heap types: Fibonacci, binary and others. + */ + { + // max + { + std::priority_queue q; + for(int n : {1,8,5,6,3,4,0,9,7,2}) + q.push(n); + assert(q.top() == 9); + q.pop(); + assert(q.top() == 8); + q.pop(); + assert(q.top() == 7); + q.pop(); + } + + // min + { + std::priority_queue, std::greater> q; + for(int n : {1,8,5,6,3,4,0,9,7,2}) + q.push(n); + assert(q.top() == 0); + q.pop(); + assert(q.top() == 1); + q.pop(); + assert(q.top() == 2); + q.pop(); + } + + // Dupes are accepted unlike in sets. + { + std::priority_queue, std::greater> q; + q.push(1); + q.push(1); + assert(q.size() == 2); + } + } +} diff --git a/cpp/interactive/.gitignore b/cpp/interactive/.gitignore new file mode 100644 index 0000000..2084151 --- /dev/null +++ b/cpp/interactive/.gitignore @@ -0,0 +1,2 @@ +/bst_vs_heap.dat +/bst_vs_heap.png diff --git a/cpp/interactive/README.md b/cpp/interactive/README.md deleted file mode 100644 index 31400e1..0000000 --- a/cpp/interactive/README.md +++ /dev/null @@ -1,4 +0,0 @@ -# Interactive - -1. [sleep_for](sleep_for.cpp) -1. [chrono](chrono.cpp) diff --git a/cpp/interactive/bst_vs_heap.cpp b/cpp/interactive/bst_vs_heap.cpp new file mode 100644 index 0000000..68a0c76 --- /dev/null +++ b/cpp/interactive/bst_vs_heap.cpp @@ -0,0 +1,58 @@ +#include "common.hpp" + +int main(int argc, char **argv) { + typedef uint64_t I; + I *randoms; + size_t i, j, n, granule; + std::priority_queue heap; + std::set bst; + std::uniform_int_distribution dist; + std::random_device dev; + unsigned int seed = dev(); + std::mt19937 prng(seed); + + if (argc > 1) { + n = std::stoi(argv[1]); + } else { + n = 1000000; + } + if (argc > 2) { + granule = std::stoi(argv[2]); + } else { + granule = 10; + } + randoms = new I[granule]; + for (i = 0; i < n / granule; ++i) { + for (j = 0; j < granule; ++j) { + randoms[j] = dist(prng); + } + + // BST. + auto start = std::chrono::high_resolution_clock::now(); + for (j = 0; j < granule; ++j) { + bst.insert(randoms[j]); + } + auto end = std::chrono::high_resolution_clock::now(); + auto dt_bst = end - start; + + // Heap. + start = std::chrono::high_resolution_clock::now(); + for (j = 0; j < granule; ++j) { + heap.emplace(randoms[j]); + } + end = std::chrono::high_resolution_clock::now(); + auto dt_heap = end - start; + + // Output. + std::cout + << std::chrono::duration_cast(dt_heap).count() << " " + << std::chrono::duration_cast(dt_bst).count() << std::endl; + } + delete[] randoms; + + // Sanity check. + for (auto it = bst.rbegin(); it != bst.rend(); ++it) { + assert(*it == heap.top()); + heap.pop(); + } +} diff --git a/cpp/interactive/bst_vs_heap.gnuplot b/cpp/interactive/bst_vs_heap.gnuplot new file mode 100755 index 0000000..c8ee2ba --- /dev/null +++ b/cpp/interactive/bst_vs_heap.gnuplot @@ -0,0 +1,10 @@ +#!/usr/bin/env gnuplot +set terminal png size 1024, 1024 +set output "bst_vs_heap.png" +set multiplot layout 2,1 title "Heap vs BST insert time" +set xlabel "size" +set ylabel "nanoseconds" +set title "Heap" +plot "bst_vs_heap.dat" using 2 notitle +set title "BST" +plot "bst_vs_heap.dat" using 3 notitle diff --git a/cpp/interactive/chrono.cpp b/cpp/interactive/chrono.cpp index 90d56db..ed1cee9 100644 --- a/cpp/interactive/chrono.cpp +++ b/cpp/interactive/chrono.cpp @@ -1,9 +1,6 @@ -/* -# chrono - -What the clocks map to in GCC Linux: -http://stackoverflow.com/questions/12392278/measure-time-in-linux-time-vs-clock-vs-getrusage-vs-clock-gettime-vs-gettimeof -*/ +/* What the clocks map to in GCC Linux: + * http://stackoverflow.com/questions/12392278/measure-time-in-linux-time-vs-clock-vs-getrusage-vs-clock-gettime-vs-gettimeof + */ #include "common.hpp" @@ -14,8 +11,10 @@ int main() { std::cout << "steady_clock::period::den = " << std::chrono::steady_clock::period::den << std::endl; std::cout << "system_clock::period::den = " << std::chrono::system_clock::period::den << std::endl; - // high_resolution_clock - // Wall clock: sleeps are counted. + /* # high_resolution_clock + * + * Wall clock: sleeps are counted. + */ { std::chrono::high_resolution_clock::time_point start_time = std::chrono::high_resolution_clock::now(); std::this_thread::sleep_for(std::chrono::seconds(1)); @@ -42,19 +41,18 @@ int main() { std::cout << "system_clock after sleep = " << std::chrono::duration_cast(dt).count() << std::endl; } - /* - # time_point - - Convertions to base types: - - - http://stackoverflow.com/questions/12835577/how-to-convert-stdchronotime-point-to-calendar-datetime-string-with-fraction - - http://stackoverflow.com/questions/33785564/how-do-i-get-seconds-since-epoch-as-a-double-given-a-time-point - - http://stackoverflow.com/questions/31255486/c-how-do-i-convert-a-stdchronotime-point-to-long-and-back - */ + /* # time_point + * + * Convertions to base types: + * + * - http://stackoverflow.com/questions/12835577/how-to-convert-stdchronotime-point-to-calendar-datetime-string-with-fraction + * - http://stackoverflow.com/questions/33785564/how-do-i-get-seconds-since-epoch-as-a-double-given-a-time-point + * - http://stackoverflow.com/questions/31255486/c-how-do-i-convert-a-stdchronotime-point-to-long-and-back + */ { std::cout << "nanoseconds since system_clock epoch = " << std::chrono::duration_cast(std::chrono::system_clock::now().time_since_epoch()).count() << std::endl; std::cout << "nanoseconds since steady_clock epoch = " << std::chrono::duration_cast(std::chrono::steady_clock::now().time_since_epoch()).count() << std::endl; } - return 0; + return 0; #endif } diff --git a/cpp/interactive/random.cpp b/cpp/interactive/random.cpp new file mode 100644 index 0000000..0b67caa --- /dev/null +++ b/cpp/interactive/random.cpp @@ -0,0 +1,19 @@ +#include "common.hpp" + +int main() { + /* # random_device + * + * Ultimate C++11 method to seed a PRNG, wraps over `/dev/urandom`. + * + * http://stackoverflow.com/questions/322938/recommended-way-to-initialize-srand/13004555#13004555 + */ + { + std::random_device dev; + unsigned int seed = dev(); + std::mt19937 prng(seed); + std::uniform_int_distribution<> dist(1, 10); + for (unsigned int i = 0; i < 10; ++i) { + std::cout << dist(prng) << std::endl; + } + } +} diff --git a/cpp/interactive/sleep_for.cpp b/cpp/interactive/sleep_for.cpp index e08ada0..55fbff9 100644 --- a/cpp/interactive/sleep_for.cpp +++ b/cpp/interactive/sleep_for.cpp @@ -1,7 +1,3 @@ -/* -# sleep_for -*/ - #include "common.hpp" int main() { diff --git a/cpp/interactive/thread_count.cpp b/cpp/interactive/thread_count.cpp index e92c606..b1804c9 100644 --- a/cpp/interactive/thread_count.cpp +++ b/cpp/interactive/thread_count.cpp @@ -1,8 +1,7 @@ -/* -Dummy operation that uses a lot of CPU, but very little memory. - -Used as a control for the parallel version, which should me scalably faster. -*/ +/* Dummy operation that uses a lot of CPU, but very little memory. + * + * Used as a control for the parallel version, which should me scalably faster. + */ #include "common.hpp" diff --git a/cpp/map.cpp b/cpp/map.cpp index 28acb6f..7e793f1 100644 --- a/cpp/map.cpp +++ b/cpp/map.cpp @@ -1,24 +1,24 @@ /* # map - http://www.cplusplus.com/reference/map/map/ +http://www.cplusplus.com/reference/map/map/ - Also comes in an unordered version `unordered_map`. +Also comes in an unordered version `unordered_map`. - Ordered. +Ordered. - Also comes in an multiple value input version `multimap`. +Also comes in an multiple value input version `multimap`. - Does not require a hash function. Usually implemented as a self balancing tree such as a rb tree. +Does not require a hash function. Usually implemented as a self balancing tree such as a rb tree. # hashmap - There seems to be no explicit hashmap container, only a generic map interface, +There seems to be no explicit hashmap container, only a generic map interface, - However unordered_map is likely to be hashmap based. +However unordered_map is likely to be hashmap based. - A nonstandard `hash_map` already provided with gcc and msvc++. - It is placed in the `std::` namespace, but it is *not* ISO. +A nonstandard `hash_map` already provided with gcc and msvc++. +It is placed in the `std::` namespace, but it is *not* ISO. */ #include "common.hpp" @@ -76,7 +76,7 @@ int main() { } /* - emplace + # emplace Put a value pair into the map without creating the pair explicitly. diff --git a/cpp/no_base_no_member.hpp b/cpp/no_base_no_member.hpp index e673e62..13897d6 100644 --- a/cpp/no_base_no_member.hpp +++ b/cpp/no_base_no_member.hpp @@ -56,7 +56,9 @@ class NoBaseNoMember { temp.i = 0; } - static void temporaryReferenceConst(const NoBaseNoMember& temp) {} + static void temporaryReferenceConst(const NoBaseNoMember& temp) { + temp.i = 0; + } }; class NoBaseNoMember0 { diff --git a/cpp/random.cpp b/cpp/random.cpp deleted file mode 100644 index 3e02809..0000000 --- a/cpp/random.cpp +++ /dev/null @@ -1,20 +0,0 @@ -#include "common.hpp" - -int main() { - /* - # random_device - - Ultimate C++11 method to seed a PRNG, wraps over `/dev/urandom`. - - http://stackoverflow.com/questions/322938/recommended-way-to-initialize-srand/13004555#13004555 - */ - { - std::random_device dev; - unsigned int seed = dev(); - std::mt19937 prng(seed); - std::uniform_int_distribution<> dist(1, 10); - for (unsigned int i = 0; i < 10; ++i) { - // std::cout << dist(prng) << std::endl; - } - } -} diff --git a/cpp/set.cpp b/cpp/set.cpp index fab1b65..d77889c 100644 --- a/cpp/set.cpp +++ b/cpp/set.cpp @@ -1,14 +1,14 @@ /* # set - - unique elements: inserting twice does nothing +Implemented with Red Black trees in GCC 6.4: +https://stackoverflow.com/questions/2558153/what-is-the-underlying-data-structure-of-a-stl-set-in-c/51944661#51944661 - - always ordered: $O(log)$ find / insert +A hashtable would be unlikely because it is sorted and can be efficiently iterated. - - immutable elements: it is not possible to modify an object, - one must first remove it and resinsert. +Unique elements: inserting twice does nothing. - This is so because modification may mean reordering. +Immutable elements: it is not possible to modify an object, one must first remove it and resinsert. This is so because modification may mean reordering. */ #include "common.hpp" @@ -81,7 +81,7 @@ int main() { /* # insert - Return is a pair conatining: + Return is a pair containing: - if the item was not present, an iterator to the item inserted and true - if the item was present, an iterator to the existing item inserted and false diff --git a/eigen/Makefile b/eigen/Makefile new file mode 120000 index 0000000..cbd0d3e --- /dev/null +++ b/eigen/Makefile @@ -0,0 +1 @@ +../Makefile_many \ No newline at end of file diff --git a/eigen/Makefile_params b/eigen/Makefile_params new file mode 100644 index 0000000..fa0330a --- /dev/null +++ b/eigen/Makefile_params @@ -0,0 +1 @@ +CXXFLAGS_EXTRA := $(shell pkg-config --cflags eigen3) diff --git a/eigen/README.md b/eigen/README.md new file mode 100644 index 0000000..d715f35 --- /dev/null +++ b/eigen/README.md @@ -0,0 +1,41 @@ +# Eigen + +https://eigen.tuxfamily.org/ + +Tested on Eigen 3.3.4. + +## SVD + +Calculate the SVD decomposition: https://en.wikipedia.org/wiki/Singular-value_decomposition + + ./svd.out + +Output: + + E + 9.52552 + 0.5143 + + U + 0.229848 -0.883461 0.408249 + 0.524745 -0.240783 -0.816496 + 0.819642 0.401896 0.408248 + + UU' + 1 -5.96046e-08 5.96046e-08 + -5.96046e-08 1 5.96046e-08 + 5.96046e-08 5.96046e-08 1 + + V + 0.61963 0.784894 + 0.784894 -0.61963 + + VV' + 1 0 + 0 1 + + least squares + -1.33333 + 1.08333 + +This shows how `U` and `V` are unitary. diff --git a/eigen/configure b/eigen/configure new file mode 100755 index 0000000..0bf6b25 --- /dev/null +++ b/eigen/configure @@ -0,0 +1,8 @@ +#!/usr/bin/env bash +sudo aptitude update +# BLAS C/Fotran and LAPACK Fortran: +sudo aptitude install liblapack-dev liblapacke-dev +# Lapack C via LAPACKE: +# TODO: how to install on Ubuntu 12.04? +# The following works only on later Ubuntu +#sudo aptitude install liblapacke-dev diff --git a/eigen/svd.cpp b/eigen/svd.cpp new file mode 100644 index 0000000..76ee651 --- /dev/null +++ b/eigen/svd.cpp @@ -0,0 +1,37 @@ +/* Adapted from: https://eigen.tuxfamily.org/dox/classEigen_1_1JacobiSVD.html */ + +#include +using std::cout; +using std::endl; + +#include +#include +using Eigen::ComputeFullU; +using Eigen::ComputeFullV; +using Eigen::DiagonalMatrix; +using Eigen::JacobiSVD; +using Eigen::MatrixXf; +using Eigen::Vector3f; + +int main() { + MatrixXf m(3,2); + m << + 1.0, 2.0, + 3.0, 4.0, + 5.0, 6.0 + ; + JacobiSVD svd(m, ComputeFullU | ComputeFullV); + auto e = svd.singularValues(); + // TODO. e needs to be 3x2, what is the nicest way? Almost there, but this changes value positions. + //MatrixXf e(svd.singularValues().asDiagonal()); + //e.resize(m.rows(), m.cols()); + cout << "E" << endl << e << endl << endl; + auto u = svd.matrixU(); + cout << "U" << endl << u << endl << endl; + cout << "UU'" << endl << u.adjoint() * u << endl << endl; + auto v = svd.matrixV(); + cout << "V" << endl << v << endl << endl; + cout << "VV'" << endl << v * v.adjoint() << endl << endl; + //cout << "UEV" << endl << u * e * v << endl << endl; + cout << "least squares" << endl << svd.solve(Vector3f(1, 0, 0)) << endl << endl; +} diff --git a/gcc/asm.c b/gcc/asm.c index 0ae76ff..d5b613c 100644 --- a/gcc/asm.c +++ b/gcc/asm.c @@ -4,57 +4,74 @@ int main(void) { #if defined(__i386__) || defined(__x86_64__) puts("__i386__ || __x86_64__"); - /* - # Basic asm vs extended asm - - There are two types of asm: basic and extended. - - The basic one does not have a colon after the string. - - Basic is strictly less powerful: it can only deal with literal commands, - so you basically (badum tish) never want to use it. - - All other examples in this section are extended asm. - - https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Extended-Asm.html - */ + /* # Basic asm vs extended asm + * + * There are two types of asm: basic and extended. + * + * The basic one does not have a colon after the string. + * + * Basic is strictly less powerful: it can only deal with literal commands, + * so you basically (badum tish) never want to use it. + * + * All other examples in this section are extended asm. + * + * https://gcc.gnu.org/onlinedocs/gcc-7.2.0/gcc/Extended-Asm.html + */ { #ifdef __i386__ - __asm__ __volatile__ ("push %eax; mov $1, %eax; pop %eax;"); + asm ("push %eax; mov $1, %eax; pop %eax;"); #else - __asm__ __volatile__ ("push %rax; mov $1, %rax; pop %rax;"); + asm ("push %rax; mov $1, %rax; pop %rax;"); #endif } - /* - # m constraint - - Memory. - - Instructs GCC to keep value of given expressions into RAM. - - This is the most basic way to get/set values of C variables in assembly code. - */ + /* # m constraint + * + * Memory. + * + * Instructs GCC to keep value of given expressions into RAM. + * + * This is the most basic way to get/set values of C variables in assembly code. + */ { - uint32_t in = 1; - uint32_t out = 0; - __asm__ __volatile__ ( - "movl %1, %%eax;" - "inc %%eax;" - "movl %%eax, %0" - : "=m" (out) /* Outputs. '=' means written to. */ - : "m" (in) /* Inputs. No '='. */ - : "%eax" - ); - assert(out == in + 1); + /* OK */ + { + uint32_t in = 1; + uint32_t out = 0; + asm ( + "movl %1, %%eax;" + "inc %%eax;" + "movl %%eax, %0" + : "=m" (out) /* Outputs. '=' means written to. */ + : "m" (in) /* Inputs. No '='. */ + : "%eax" + ); + assert(out == in + 1); + } + + /* ERROR: memory input 1 is not directly addressable */ + /* + { + uint32_t out = 0; + asm ( + "movl %1, %%eax;" + "inc %%eax;" + "movl %%eax, %0" + : "=m" (out) + : "m" (1) + : "%eax" + ); + assert(out == 1 + 1); + } + */ } - /* Multiple inputs. */ - { + /* Multiple inputs. */ + { uint32_t in0 = 1; uint32_t in1 = 2; uint32_t out = 0; - __asm__ __volatile__ ( + asm ( "movl %1, %%eax;" "movl %2, %%ebx;" "addl %%ebx, %%eax;" @@ -74,13 +91,13 @@ int main(void) { * We must mark it as `+` which means that the memory is used for both read and write. */ { uint32_t io = 0; - __asm__ __volatile__ ( - "movl %0, %%eax;" - "inc %%eax;" - "movl %%eax, %0;" - : "+m" (io) /* + means both read and written to. */ - : /* No input. */ - : "%eax" + asm ( + "movl %0, %%eax;" + "inc %%eax;" + "movl %%eax, %0;" + : "+m" (io) /* + means both read and written to. */ + : /* No input. */ + : "%eax" ); assert(io == 1); } @@ -90,7 +107,7 @@ int main(void) { float in = 1.0; float out = 0.0; /* out = -in */ - __asm__ __volatile__ ( + asm ( "flds %1;" "fchs;" "fstps %0;" @@ -100,40 +117,38 @@ int main(void) { assert(out == -1.0); } - /* - # Register constraints - - https://gcc.gnu.org/onlinedocs/gcc/Simple-Constraints.html - - Tell GCC to automatically read memory into registers or write registers into memory - - This is more precise and complicated than using `m`: - - - r: gcc chooses any free register - - a: %eax - - b: %ebx - - c: %ecx - - d: %edx - - S: %esi - - D: %edi - - 0: matching register - */ - - /* - # r register constraint - - GCC will automatically put the value of `in` from RAM into a register for us - and `out` from a register into ram at the end - - GCC just makes sure they are written from/to memory before/after the operations. - - This is great, as it: - - - makes our assembly shorter: no memory moves nor clobbers are needed - - allows GCC to optimize further - */ + /* # Register constraints + * + * https://gcc.gnu.org/onlinedocs/gcc/Simple-Constraints.html + * + * Tell GCC to automatically read memory into registers or write registers into memory + * + * This is more precise and complicated than using `m`: + * + * - r: gcc chooses any free register + * - a: %eax + * - b: %ebx + * - c: %ecx + * - d: %edx + * - S: %esi + * - D: %edi + * - 0: matching register + */ + + /* # r register constraint + * + * GCC will automatically put the value of `in` from RAM into a register for us + * and `out` from a register into ram at the end + * + * GCC just makes sure they are written from/to memory before/after the operations. + * + * This is great, as it: + * + * - makes our assembly shorter: no memory moves nor clobbers are needed + * - allows GCC to optimize further + */ { - const uint32_t in0 = 0; + const uint32_t in0 = 0; uint32_t in = in0; uint32_t out = 0; asm ( @@ -148,17 +163,17 @@ int main(void) { } /* - # 0 matching constraint - - Specifies that an input maps to the same as a given output. - - https://stackoverflow.com/questions/48381184/can-i-modify-input-operands-in-gcc-inline-assembly/48381252#48381252 - - - vs '+': allows biding two different variables - - vs 'a': allows referring to an 'r', which is automatically allocated by GCC - */ + * # 0 matching constraint + * + * Specifies that an input maps to the same as a given output. + * + * https://stackoverflow.com/questions/48381184/can-i-modify-input-operands-in-gcc-inline-assembly/48381252#48381252 + * + * - vs '+': allows biding two different variables + * - vs 'a': allows referring to an 'r', which is automatically allocated by GCC + */ { - const uint32_t in0 = 1; + const uint32_t in0 = 1; uint32_t in = in0; uint32_t out = 0; asm ( @@ -170,15 +185,14 @@ int main(void) { assert(out == in0 + 1); } - /* - # a register constraint - - Forces it to be put into eax. - - Clobber done automatically for us. - - Just use 'r' whenever you can. - */ + /* # a register constraint + * + * Forces it to be put into eax. + * + * Clobber done automatically for us. + * + * Just use 'r' whenever you can. + */ { uint32_t x = 0; asm ( @@ -189,13 +203,12 @@ int main(void) { assert(x == 1); } - /* - # Register variables - - http://stackoverflow.com/questions/2114163/reading-a-register-value-into-a-c-variable - - https://gcc.gnu.org/onlinedocs/gcc-4.4.2/gcc/Explicit-Reg-Vars.html - */ + /* # Register variables + * + * http://stackoverflow.com/questions/2114163/reading-a-register-value-into-a-c-variable + * + * https://gcc.gnu.org/onlinedocs/gcc-4.4.2/gcc/Explicit-Reg-Vars.html + */ { register uint32_t eax asm ("eax"); asm ("mov $1, %%eax;" : : : "%eax"); diff --git a/gcc/asm.md b/gcc/asm.md index 7eab1e2..2c040bf 100644 --- a/gcc/asm.md +++ b/gcc/asm.md @@ -45,9 +45,10 @@ where: Both inputs and outputs are constraints. `X` will indicate the constraint type -# __asm__ vs asm +## __asm__ vs asm - +- +- ## Double percent diff --git a/gcc/build.md b/gcc/build.md index 7fe38c8..a83091a 100644 --- a/gcc/build.md +++ b/gcc/build.md @@ -4,35 +4,36 @@ How to build GCC from source. Tested with: version 5.1.0 on Ubuntu 14.04 in a 2013 computer. -Summary: +Summary local build: sudo apt-get build-dep gcc # Required to compile gnat. sudo apt-get install gnat-4.8 - mkdir gcc + git clone git://gcc.gnu.org/git/gcc.git cd gcc - git clone git://gcc.gnu.org/git/gcc.git src - cd src # No annotated tags... so no describe. git checkout gcc-5_1_0-release ./contrib/download_prerequisites - cd .. mkdir build cd build # C and C++ only. - ../src/configure --enable-languages=c,c++ --prefix="$(pwd)/../install" + ../configure --enable-languages=c,c++ --prefix="$(pwd)/install" # Add a suffix to the executable names: # --program-suffix="-4.7" # All languages. - # ../src/configure --enable-languages=all --prefix="$(pwd)/../install" + # ../configure --enable-languages=all --prefix="$(pwd)/install" # Wait hours. - make -j5 + make -j$(nproc) + # Wait hours. - make check + #make check + # Install executables to /usr/local/bin # There are also many other installed files under /usr/local. - sudo make install - gcc -v + make install + + # Use it. + ./install/bin/gcc -v # sudo update-alternatives --install /usr/bin/gcc gcc /usr/bin/gcc-4.9 60 --slave /usr/bin/g++ g++ /usr/bin/g++-4.9 Or install locally for interactive testing: diff --git a/gcc/statement_expression.c b/gcc/statement_expression.c index 25e1c9d..9109f23 100644 --- a/gcc/statement_expression.c +++ b/gcc/statement_expression.c @@ -1,14 +1,35 @@ /* -## Statement expression +# Statement expression - https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html +Only the last expression is "returned". - Only the last expression is returned. +Especially useful for macros: +https://stackoverflow.com/questions/10393844/about-typecheck-in-linux-kernel +where it serves as a "return value" + +https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html */ +#define FACTORIAL(X) \ + ({ \ + unsigned int x = X; \ + unsigned int result = 1; \ + while (x > 1) { \ + result *= x; \ + x--; \ + } \ + result; \ + }) + #include "common.h" int main() { - assert(({int i = 0; int j = i; i++; j = i; j;})); + /* Minimal example */ + int x = ({int i = 0; i++; i + 1;}); + assert(x == 2); + + /* More meaningful macro example*/ + assert(FACTORIAL(5) == 120); + return EXIT_SUCCESS; } diff --git a/gcc/typeof.c b/gcc/typeof.c index b47ee43..d3df245 100644 --- a/gcc/typeof.c +++ b/gcc/typeof.c @@ -1,9 +1,11 @@ /* # typeof - Like C++11 decltype. +Like C++11 decltype. - Partially reproductible with C11 `_Generic`. +Partially reproductible with C11 `_Generic`. + +https://stackoverflow.com/questions/6513806/would-it-be-possible-to-add-type-inference-to-the-c-language/31709221#31709221 */ #include "common.h" @@ -12,5 +14,10 @@ int main() { /* Same as: double j = 0.5; */ typeof(1 + 0.5) j = 0.5; assert(j == 0.5); + + /* Similar to C++ auto. */ + __auto_type k = 0.5; + assert(sizeof(j) == sizeof(k)); + return EXIT_SUCCESS; } diff --git a/gdb/Makefile b/gdb/Makefile index 8b66f0a..6981794 100644 --- a/gdb/Makefile +++ b/gdb/Makefile @@ -1,27 +1,30 @@ .POSIX: -G ?= gdb3 -IN_EXT ?= .c -IN_EXT_CPP ?= .cpp -O ?= 0 -OUT_EXT ?= .out -RUN ?= count_infinite - -INS := $(wildcard *$(IN_EXT)) -OUTS := $(addsuffix $(OUT_EXT), $(basename $(INS))) - -INS_CPP := $(wildcard *$(IN_EXT_CPP)) -OUTS_CPP := $(addsuffix $(OUT_EXT), $(basename $(INS_CPP))) +COMMON_FLAGS = -O'$O' -g'$(G)' -pthread -Wextra +CFLAGS = $(COMMON_FLAGS) -std=c99 +CXXFLAGS = $(COMMON_FLAGS) -std=c++11 +G = gdb3 +IN_EXT = .c +IN_EXT_CPP = .cpp +O = 0 +OUT_EXT = .out +RUN = count_infinite + +INS = $(wildcard *$(IN_EXT)) +OUTS = $(addsuffix $(OUT_EXT), $(basename $(INS))) + +INS_CPP = $(wildcard *$(IN_EXT_CPP)) +OUTS_CPP = $(addsuffix $(OUT_EXT), $(basename $(INS_CPP))) .PHONY: all clean run all: $(OUTS) $(OUTS_CPP) %$(OUT_EXT): %$(IN_EXT) - gcc -O'$O' -g'$(G)' -o '$@' -pedantic-errors -std=c89 -Wextra '$<' + gcc $(CFLAGS) -o '$@' -pedantic-errors '$<' %$(OUT_EXT): %$(IN_EXT_CPP) - g++ -O'$O' -g'$(G)' -o '$@' -pedantic-errors -std=c++11 -Wextra '$<' + g++ $(CXXFLAGS) -o '$@' -pedantic-errors '$<' clean: rm -f *$(OUT_EXT) diff --git a/gdb/README.md b/gdb/README.md index 661e00a..4f03d5b 100644 --- a/gdb/README.md +++ b/gdb/README.md @@ -29,6 +29,7 @@ Tested on 7.7.1 unless mentioned otherwise. 1. [Overload](overload.cpp) 1. [Method](method.cpp) 1. [Polymorphism](polymorphism.cpp) + 1. [Threads](threads.c) 1. [gdbserver](gdbserver.md) 1. GDB scripts 1. [step_all](step_all.gdb) diff --git a/gdb/run b/gdb/run index 4e725e9..ad38e81 100755 --- a/gdb/run +++ b/gdb/run @@ -1,11 +1,10 @@ #!/usr/bin/env bash - -# Usage: try either of: -# -# run watch -# run watch. -# run watch.c -# run watch.out - +set -eu f="${1%.*}" -gdb -batch -nh -x "${f}.gdb" "${f}.out" +g="${f}.gdb" +if [ -f "$g" ]; then + gdbcmd="-batch -x $g" +else + gdbcmd= +fi +gdb -nh -q $gdbcmd "${f}.out" diff --git a/gdb/threads.c b/gdb/threads.c new file mode 100644 index 0000000..95d77da --- /dev/null +++ b/gdb/threads.c @@ -0,0 +1,47 @@ +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include + +void* thread_0(void *arg) { + int i; + i = 0; + while (true) { + printf("t0 %d\n", i); + sleep(1); + i++; + } + return NULL; +} + +void* thread_1(void *arg) { + int i; + i = 0; + while (true) { + printf("t1 %d\n", i); + sleep(1); + i++; + } + return NULL; +} + +int main(void) { + enum NUM_THREADS {NUM_THREADS = 2}; + pthread_t threads[NUM_THREADS]; + int thread_args[NUM_THREADS]; + int i; + pthread_create(&threads[0], NULL, thread_0, (void*)&thread_args[0]); + pthread_create(&threads[1], NULL, thread_1, (void*)&thread_args[1]); + pthread_setname_np(threads[1], "myname1"); + while (true) { + printf("main %d\n", i); + sleep(1); + i++; + } + return EXIT_SUCCESS; +} diff --git a/gdb/threads.md b/gdb/threads.md new file mode 100644 index 0000000..12450b6 --- /dev/null +++ b/gdb/threads.md @@ -0,0 +1,94 @@ +# Threads + +Run: + + ./run threads + +Inside GDB: + + run + +Then: + + Ctrl + C + +All threads stop. + +## Get backtraces for all threads + +https://stackoverflow.com/questions/18391808/how-to-get-the-backtrace-for-all-the-threads-in-gdb + + thread apply all bt + +Sample output: + + Thread 3 (Thread 0x7ffff6fee700 (LWP 29344)): + #0 0x00007ffff78bc30d in nanosleep () at ../sysdeps/unix/syscall-template.S:84 + #1 0x00007ffff78bc25a in __sleep (seconds=0) at ../sysdeps/posix/sleep.c:55 + #2 0x0000000000400839 in thread_1 (arg=0x7fffffffcf0c) at threads.c:33 + #3 0x00007ffff7bc16ba in start_thread (arg=0x7ffff6fee700) at pthread_create.c:333 + #4 0x00007ffff78f741d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 + + Thread 2 (Thread 0x7ffff77ef700 (LWP 29343)): + #0 0x00007ffff78bc30d in nanosleep () at ../sysdeps/unix/syscall-template.S:84 + #1 0x00007ffff78bc25a in __sleep (seconds=0) at ../sysdeps/posix/sleep.c:55 + #2 0x000000000040075b in thread_0 (arg=0x7fffffffcf08) at threads.c:19 + #3 0x00007ffff7bc16ba in start_thread (arg=0x7ffff77ef700) at pthread_create.c:333 + #4 0x00007ffff78f741d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:109 + + Thread 1 (Thread 0x7ffff7fc7700 (LWP 29339)): + #0 nanosleep () at ../sysdeps/unix/syscall-template.S:85 + #1 0x00007ffff78bc25a in __sleep (seconds=0) at ../sysdeps/posix/sleep.c:55 + #2 0x00000000004008b9 in main () at threads.c:48 + +So we see that there are three threads: + +- `1` which is the `main` +- `2` and `3` which we created ourselves + +all of which are very likely inside sleep. + +A few more information we can extract: + + LWP 29339 + +means: + +- `LWP`: Light Weight Process +- `29339`: thread ID + +If we also get the process ID with : + + info inferior + +then we can confirm the thread ID under `/proc`: + + ls /proc//task/ + +The part: + + Thread 0x7ffff77ef700 + +gives us value of `pthread_t` . This can be confirmed with: + + thread 1 + up 2 + p/x threads + +## More basic things + +Switch to a thread: + + thread 1 + +Now the usual commands like `bt`, `info registers`, etc. will apply to that thread. + +List all threads: + + info threads + +This shows one extra information that `thread apply all bt` does not: the thread name: + + myname1 + +which defaults to the executable name, but which we have modified for the thread 1 with `pthread_setname_np`, see also: diff --git a/glibc/README.md b/glibc/README.md index 54408ff..c1b52f8 100644 --- a/glibc/README.md +++ b/glibc/README.md @@ -7,6 +7,7 @@ 1. [main.c](main.c) 1. [ptrace.c](ptrace.c) 1. [reboot.c](reboot.c.off) + 1. [sched.c](sched.c) 1. [syscall.c](syscall.c) 1. `string.h` 1. [strverscmp.c](strverscmp.c) diff --git a/glibc/main.c b/glibc/main.c index c1f126e..e2d198f 100644 --- a/glibc/main.c +++ b/glibc/main.c @@ -66,51 +66,6 @@ int main() { } } - /* - # sched.h - - More scheduling policies are defined. - - Those constants have the same meaning as in the kernel code versions. - */ - { - printf("SCHED_BATCH = %d\n", SCHED_BATCH); - printf("SCHED_IDLE = %d\n", SCHED_IDLE ); - - /* Called SCHED_NORMAL in the kernel: */ - printf("SCHED_OTHER = %d\n", SCHED_OTHER); - - /* - # sched_getaffinity - - view in which cpu's the given process can run - - Linux keeps track of this, and this can be set with appropriate premissions - - # sched_setaffinity - - set for getaffinity - - # cpu_set_t - - a bitmap with a field per cpu - */ - { - cpu_set_t mask; - if (sched_getaffinity(0, sizeof(cpu_set_t), &mask) == -1) { - perror("sched_getaffinity"); - exit(EXIT_FAILURE); - } else { - printf("sched_getaffinity = "); - unsigned int i; - for (i = 0; i < sizeof(cpu_set_t); i++) { - printf("%d", CPU_ISSET(0, &mask)); - } - printf("\n"); - } - } - } - /* # unistd.h */ diff --git a/glibc/sched.c b/glibc/sched.c new file mode 100644 index 0000000..b92f001 --- /dev/null +++ b/glibc/sched.c @@ -0,0 +1,69 @@ +/* +- https://stackoverflow.com/questions/10490756/how-to-use-sched-getaffinity2-and-sched-setaffinity2-please-give-code-samp +- https://stackoverflow.com/questions/766395/how-does-sched-setaffinity-work +- https://stackoverflow.com/questions/8336191/how-to-prevent-inheriting-cpu-affinity-by-child-forked-process +- https://unix.stackexchange.com/questions/73/how-can-i-set-the-processor-affinity-of-a-process-on-linux/441098#441098 + +Also try to this program with something like: + + taskset -c 1-3 ./sched.out + +# sched.h + + More scheduling policies are defined. + + Those constants have the same meaning as in the kernel code versions. +*/ + +#include "common.h" + +void print_affinity() { + cpu_set_t mask; + long nproc, i; + + if (sched_getaffinity(0, sizeof(cpu_set_t), &mask) == -1) { + perror("sched_getaffinity"); + assert(false); + } else { + nproc = sysconf(_SC_NPROCESSORS_ONLN); + printf("sched_getaffinity = "); + for (i = 0; i < nproc; i++) { + printf("%d ", CPU_ISSET(i, &mask)); + } + printf("\n"); + } +} + +int main(void) { + printf("SCHED_BATCH = %d\n", SCHED_BATCH); + printf("SCHED_IDLE = %d\n", SCHED_IDLE ); + /* Called SCHED_NORMAL in the kernel: */ + printf("SCHED_OTHER = %d\n", SCHED_OTHER); + + /* + # sched_getaffinity + + View in which cpu's the given process can run. + + Linux keeps track of this, and this can be set with appropriate premissions. + + 0 means getpid(). + */ + { + cpu_set_t mask; + + print_affinity(); + printf("sched_getcpu = %d\n", sched_getcpu()); + CPU_ZERO(&mask); + CPU_SET(0, &mask); + if (sched_setaffinity(0, sizeof(cpu_set_t), &mask) == -1) { + perror("sched_setaffinity"); + assert(false); + } + print_affinity(); + /* TODO is it guaranteed to have taken effect already? Always worked on my tests. */ + printf("sched_getcpu = %d\n", sched_getcpu()); + } + + return EXIT_SUCCESS; +} diff --git a/lapack/c.c b/lapack/c.c index 0d37554..0d50e09 100644 --- a/lapack/c.c +++ b/lapack/c.c @@ -1,8 +1,8 @@ /* -How to use blas and lapack with the standard -interfaces provided by their respective projects, repectively through -`cblas.h` and `lapacke.h` -*/ + * How to use blas and lapack with the standard + * interfaces provided by their respective projects, repectively through + * `cblas.h` and `lapacke.h` + */ #include #include @@ -13,8 +13,7 @@ interfaces provided by their respective projects, repectively through #include #include -/** - * assert two integers are equal +/* Assert two integers are equal. * if not, print them to stderr and assert false */ void assert_eqi(int i1, int i2) { @@ -24,9 +23,8 @@ void assert_eqi(int i1, int i2) { } } -/** - * assert two doubles are equal within err precision - * if not, print them to stderr +/* Assert two doubles are equal within err precision + * If not, print them to stderr */ void assert_eqd(double d1, double d2, double err) { if (fabs(d1 - d2) > err) { @@ -35,7 +33,7 @@ void assert_eqd(double d1, double d2, double err) { } } -/** print an array of doubles to stderr */ +/* print an array of doubles to stderr */ void print_vecd(int n, double * v) { int i; for (i=0; i 0 + scons x=1 + ./main.out + # => 1 + scons x=0 + ./main.out + # => 0 diff --git a/scons/default/README.md b/scons/default/README.md new file mode 100644 index 0000000..439dbd9 --- /dev/null +++ b/scons/default/README.md @@ -0,0 +1,21 @@ +# Default + + cd src0 + + scons + ./main.out + # => No such file or directory. + ../src1/main.out + # => 1 + + scons .. + ./main.out + # => 0 + ../src1/main.out + # => 1 + +By default, SCons builds all targets under the current directory and descendants. + +If `Default()` is given, it change that default to the given programs. + +You can always go back to recurse under a given directory with `scons path/to/dir`. diff --git a/scons/default/src0/SConstruct b/scons/default/src0/SConstruct new file mode 100644 index 0000000..737f8f2 --- /dev/null +++ b/scons/default/src0/SConstruct @@ -0,0 +1,4 @@ +env = Environment() +p0 = env.Program(target='main.out', source=['main.c']) +p1 = env.Program(target='../src1/main.out', source=['../src1/main.c']) +env.Default(p1) diff --git a/scons/default/src0/main.c b/scons/default/src0/main.c new file mode 100644 index 0000000..62130df --- /dev/null +++ b/scons/default/src0/main.c @@ -0,0 +1,5 @@ +#include + +int main(void) { + puts("0"); +} diff --git a/scons/default/src1/main.c b/scons/default/src1/main.c new file mode 100644 index 0000000..270e419 --- /dev/null +++ b/scons/default/src1/main.c @@ -0,0 +1,5 @@ +#include + +int main(void) { + puts("1"); +} diff --git a/scons/sconscript/README.md b/scons/sconscript/README.md new file mode 100644 index 0000000..6fd4c05 --- /dev/null +++ b/scons/sconscript/README.md @@ -0,0 +1,4 @@ +# SConscript + + scons + ./src/main.out diff --git a/scons/sconscript/SConstruct b/scons/sconscript/SConstruct new file mode 100644 index 0000000..272066f --- /dev/null +++ b/scons/sconscript/SConstruct @@ -0,0 +1,2 @@ +env = Environment() +env.SConscript('src/SConscript') diff --git a/scons/sconscript/scr b/scons/sconscript/scr new file mode 100644 index 0000000..00af2ff --- /dev/null +++ b/scons/sconscript/scr @@ -0,0 +1,5 @@ +#include + +int main(void) { + puts("hello"); +} diff --git a/scons/sconscript/src/SConscript b/scons/sconscript/src/SConscript new file mode 100644 index 0000000..5bc2b34 --- /dev/null +++ b/scons/sconscript/src/SConscript @@ -0,0 +1,2 @@ +env = Environment() +env.Program(target='main.out', source=['main.c']) diff --git a/scons/sconscript/src/main.c b/scons/sconscript/src/main.c new file mode 100644 index 0000000..00af2ff --- /dev/null +++ b/scons/sconscript/src/main.c @@ -0,0 +1,5 @@ +#include + +int main(void) { + puts("hello"); +} diff --git a/scons/two-envs/README.md b/scons/two-envs/README.md new file mode 100644 index 0000000..a765be1 --- /dev/null +++ b/scons/two-envs/README.md @@ -0,0 +1,9 @@ +# Two envs + +All declared envs with `Environment()` are built: + + scons + ./build-0/main.out + # => 0 + ./build-1/main.out + # => 1 diff --git a/scons/two-envs/SConstruct b/scons/two-envs/SConstruct new file mode 100644 index 0000000..e60871c --- /dev/null +++ b/scons/two-envs/SConstruct @@ -0,0 +1,14 @@ +import os.path + +def mkenv(x): + env = Environment() + env.Append(CPPDEFINES=['X=' + x]) + variant_dir = 'build-{}'.format(x) + env.VariantDir(variant_dir, 'src', duplicate=0) + program = env.Program( + target=os.path.join(variant_dir, 'main.out'), + source=[os.path.join(variant_dir, 'main.c')] + ) + +mkenv('0') +mkenv('1') diff --git a/scons/two-envs/src/main.c b/scons/two-envs/src/main.c new file mode 100644 index 0000000..1d9e19c --- /dev/null +++ b/scons/two-envs/src/main.c @@ -0,0 +1,5 @@ +#include + +int main(void) { + printf("%d\n", X); +} diff --git a/scons/variant-dir/README.md b/scons/variant-dir/README.md new file mode 100644 index 0000000..ebcae40 --- /dev/null +++ b/scons/variant-dir/README.md @@ -0,0 +1,13 @@ +# Variant dir + + scons + ./build-0/main.out + # => 0 + scons x=1 + ./build-1/main.out + # => 1 + +We could do something more advanced by: + +- hash all input arguments like `x` and name the output directory after them +- cat the input arguments to a file in that directory to enable identifying the directories diff --git a/scons/variant-dir/SConstruct b/scons/variant-dir/SConstruct new file mode 100644 index 0000000..2546784 --- /dev/null +++ b/scons/variant-dir/SConstruct @@ -0,0 +1,10 @@ +import os.path +env = Environment() +x = ARGUMENTS.get('x', '0') +env.Append(CPPDEFINES=['X=' + x]) +variant_dir = 'build-{}'.format(x) +env.VariantDir(variant_dir, 'src', duplicate=0) +program1 = env.Program( + target=os.path.join(variant_dir, 'main.out'), + source=[os.path.join(variant_dir, 'main.c')] +) diff --git a/scons/variant-dir/src/main.c b/scons/variant-dir/src/main.c new file mode 100644 index 0000000..1d9e19c --- /dev/null +++ b/scons/variant-dir/src/main.c @@ -0,0 +1,5 @@ +#include + +int main(void) { + printf("%d\n", X); +} diff --git a/sdl/png.c b/sdl/png.c index 7aac1dc..2b11a5c 100644 --- a/sdl/png.c +++ b/sdl/png.c @@ -1,13 +1,13 @@ - -/* -Basic texture example. - -Much faster than SDL_RenderDrawPoint calls. - -Uses GL textures under the hood. - -SDL_TEXTUREACCESS_STREAMING is key to allow us to write to the texture from CPU. -*/ +/* Basic texture example. + * + * Much faster than SDL_RenderDrawPoint calls. + * + * Uses GL textures under the hood. + * + * SDL_TEXTUREACCESS_STREAMING is key to allow us to write to the texture from CPU. + * + * https://gamedev.stackexchange.com/questions/59078/sdl-function-for-loading-pngs/135894#135894 + */ #include "common.h" diff --git a/shared-library/basic/Makefile b/shared-library/basic/Makefile index c566df9..fd8bf08 100644 --- a/shared-library/basic/Makefile +++ b/shared-library/basic/Makefile @@ -1,13 +1,15 @@ -CC := gcc -ggdb3 -pedantic-errors -std=c89 -Wall -Wextra +CC_DL = gcc -ggdb3 -std=c89 -Wall -Wextra +CC = $(CC_DL) -pedantic-errors .PHONY: all clean run -all: maina.out mainso.out mainso_fullpath.out +all: maina.out mainso.out mainso_fullpath.out dlopen.out run: all ./maina.out LD_LIBRARY_PATH=. ./mainso.out ./mainso_fullpath.out + LD_LIBRARY_PATH=. ./dlopen.out mainso.out: main.o libcirosantilli_ab.so @# Will look for lib with basename *exactly* `libcirosantilli_ab.so`, @@ -37,6 +39,17 @@ mainso_fullpath.out: main.o libcirosantilli_ab.so maina.out: main.o ab.a $(CC) main.o ab.a -o maina.out +# If we use -pedantic-errors, build fails: +# +# ISO C forbids conversion of object pointer to function pointer type +# +# There seems to be no no undefined way of doing it: +# https://stackoverflow.com/questions/14134245/iso-c-void-and-function-pointers +# +# -dl required otherwise: https://stackoverflow.com/questions/956640/linux-c-error-undefined-reference-to-dlopen +dlopen.out: dlopen.c + $(CC_DL) -o '$@' '$<' -ldl + libcirosantilli_ab.so: a.o b.o $(CC) -shared a.o b.o -o libcirosantilli_ab.so @# Same? diff --git a/shared-library/basic/README.md b/shared-library/basic/README.md index ae53e55..f0083a5 100644 --- a/shared-library/basic/README.md +++ b/shared-library/basic/README.md @@ -1,7 +1,3 @@ # Basic -Basic example. Creates a shared and a static library from `a.c` and `b.c`, and uses them in the following ways: - -- `maina.out`: uses the static library -- `mainso.out`: uses the `.so` library with basename only -- `mainso_fullpath.out`: uses the `.so` with the fullpath +Basic example. Creates a shared and a static library from `a.c` and `b.c`. diff --git a/shared-library/basic/a.c b/shared-library/basic/a.c index b7dcf22..f8cc9b0 100644 --- a/shared-library/basic/a.c +++ b/shared-library/basic/a.c @@ -1,12 +1,9 @@ -#include - -/* -Not mandatory in this example since we define the function here. - -But still a good idea to ensure that the prototypes are compatible. - -Often required because of header struct declarations. -*/ +/* Not mandatory in this example since we define the function here. + * + * But still a good idea to ensure that the prototypes are compatible. + * + * Often required because of header struct declarations. + */ #include "a.h" -void a(void) { puts("a"); } +int a(void) { return 1; } diff --git a/shared-library/basic/a.h b/shared-library/basic/a.h index 733fc06..d72f9ff 100644 --- a/shared-library/basic/a.h +++ b/shared-library/basic/a.h @@ -1,6 +1,6 @@ #ifndef A_H #define A_H -void a(void); +int a(void); #endif diff --git a/shared-library/basic/b.c b/shared-library/basic/b.c index e1d66d3..f5ece7c 100644 --- a/shared-library/basic/b.c +++ b/shared-library/basic/b.c @@ -1,5 +1,3 @@ -#include - #include "b.h" -void b(void) { puts("b"); } +int b(void) { return 2; } diff --git a/shared-library/basic/b.h b/shared-library/basic/b.h index 9bc5877..495df22 100644 --- a/shared-library/basic/b.h +++ b/shared-library/basic/b.h @@ -1,6 +1,6 @@ #ifndef B_H #define B_H -void b(void); +int b(void); #endif diff --git a/shared-library/basic/dlopen.c b/shared-library/basic/dlopen.c new file mode 100644 index 0000000..cd53b64 --- /dev/null +++ b/shared-library/basic/dlopen.c @@ -0,0 +1,33 @@ +#define _XOPEN_SOURCE 700 +#include +#include +#include +#include + +#include "a.h" +#include "b.h" + +int main() { + void *handle; + int (*a)(void); + int (*b)(void); + char *error; + + handle = dlopen("libcirosantilli_ab.so", RTLD_LAZY); + if (!handle) { + fprintf(stderr, "%s\n", dlerror()); + exit(EXIT_FAILURE); + } + dlerror(); + a = (int (*)(void)) dlsym(handle, "a"); + b = (int (*)(void)) dlsym(handle, "b"); + error = dlerror(); + if (error != NULL) { + fprintf(stderr, "%s\n", error); + exit(EXIT_FAILURE); + } + assert(a() == 1); + assert(b() == 2); + dlclose(handle); + return EXIT_SUCCESS; +} diff --git a/shared-library/basic/main.c b/shared-library/basic/main.c index b2da9e2..1041d63 100644 --- a/shared-library/basic/main.c +++ b/shared-library/basic/main.c @@ -1,11 +1,11 @@ -#include +#include #include #include "a.h" #include "b.h" int main(void) { - a(); - b(); + assert(a() == 1); + assert(b() == 2); return EXIT_SUCCESS; } diff --git a/shared-library/lib-lib-dependency/a.c b/shared-library/lib-lib-dependency/a.c index 2d6349f..0800b98 100644 --- a/shared-library/lib-lib-dependency/a.c +++ b/shared-library/lib-lib-dependency/a.c @@ -3,7 +3,6 @@ #include "a.h" #include "b.h" -void a(void) { - puts("a"); - b(); +int a(void) { + return b() + 1; } diff --git a/shared-library/lib-lib-dependency/a.h b/shared-library/lib-lib-dependency/a.h index 733fc06..d72f9ff 100644 --- a/shared-library/lib-lib-dependency/a.h +++ b/shared-library/lib-lib-dependency/a.h @@ -1,6 +1,6 @@ #ifndef A_H #define A_H -void a(void); +int a(void); #endif diff --git a/shared-library/lib-lib-dependency/b.c b/shared-library/lib-lib-dependency/b.c index e1d66d3..48785b3 100644 --- a/shared-library/lib-lib-dependency/b.c +++ b/shared-library/lib-lib-dependency/b.c @@ -2,4 +2,4 @@ #include "b.h" -void b(void) { puts("b"); } +int b(void) { return 2; } diff --git a/shared-library/lib-lib-dependency/b.h b/shared-library/lib-lib-dependency/b.h index 9bc5877..495df22 100644 --- a/shared-library/lib-lib-dependency/b.h +++ b/shared-library/lib-lib-dependency/b.h @@ -1,6 +1,6 @@ #ifndef B_H #define B_H -void b(void); +int b(void); #endif diff --git a/shared-library/lib-lib-dependency/main.c b/shared-library/lib-lib-dependency/main.c index a13aaf4..9fdb940 100644 --- a/shared-library/lib-lib-dependency/main.c +++ b/shared-library/lib-lib-dependency/main.c @@ -1,9 +1,9 @@ -#include +#include #include #include "a.h" int main(void) { - a(); + assert(a() == 3); return EXIT_SUCCESS; } diff --git a/shared-library/symbol-version/Makefile b/shared-library/symbol-version/Makefile index 0074460..d0fc3dc 100644 --- a/shared-library/symbol-version/Makefile +++ b/shared-library/symbol-version/Makefile @@ -18,6 +18,9 @@ main1.out: main.c libcirosantilli_a.so main2.out: main.c libcirosantilli_a.so $(CC) -DV2 -L'.' main.c -o '$@' -lcirosantilli_a +a.o: a.c + $(CC) -fPIC -c '$<' -o '$@' + libcirosantilli_a.so: a.o $(CC) -Wl,--version-script,a.map -L'.' -shared a.o -o '$@' diff --git a/shared-library/symbol-version/README.md b/shared-library/symbol-version/README.md index cdc1017..a8167fe 100644 --- a/shared-library/symbol-version/README.md +++ b/shared-library/symbol-version/README.md @@ -4,4 +4,4 @@ Trying to replicate glibc's `symbol@@VERSION` madness. This allows you to have a single library `v2`, that also contains symbols from `v1`. - contains a nice example. + diff --git a/shared-library/symbol-version/a.c b/shared-library/symbol-version/a.c index 147c8c2..51ff562 100644 --- a/shared-library/symbol-version/a.c +++ b/shared-library/symbol-version/a.c @@ -1,14 +1,12 @@ -#include - #include "a.h" __asm__(".symver a1,a@LIBA_1"); -void a1(void) { - puts("a1"); +int a1(void) { + return 1; } /* @@ means "default version". */ __asm__(".symver a2,a@@LIBA_2"); -void a2(void) { - puts("a2"); +int a2(void) { + return 2; } diff --git a/shared-library/symbol-version/a.h b/shared-library/symbol-version/a.h index 733fc06..d72f9ff 100644 --- a/shared-library/symbol-version/a.h +++ b/shared-library/symbol-version/a.h @@ -1,6 +1,6 @@ #ifndef A_H #define A_H -void a(void); +int a(void); #endif diff --git a/shared-library/symbol-version/main.c b/shared-library/symbol-version/main.c index 58048ed..26b0221 100644 --- a/shared-library/symbol-version/main.c +++ b/shared-library/symbol-version/main.c @@ -1,4 +1,4 @@ -#include +#include #include #include "a.h" @@ -12,6 +12,10 @@ __asm__(".symver a,a@LIBA_2"); #endif int main(void) { - a(); +#if defined(V1) + assert(a() == 1); +#else + assert(a() == 2); +#endif return EXIT_SUCCESS; }