bprint: add av_bprint_init_for_buffer().

libavutil/bprint.c

@@ -78,6 +78,15 @@ void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
  av_bprint_alloc(buf, size_init - 1);
 }
 
+void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size)
+{
+ buf->str = buffer;
+ buf->len = 0;
+ buf->size = size;
+ buf->size_max = size;
+ *buf->str = 0;
+}
+
 void av_bprintf(AVBPrint *buf, const char *fmt, ...)
 {
  unsigned room;
@@ -178,6 +187,7 @@ static void bprint_pascal(AVBPrint *b, unsigned size)
 int main(void)
 {
  AVBPrint b;
+ char buf[256];
 
  av_bprint_init(&b, 0, -1);
  bprint_pascal(&b, 5);
@@ -208,6 +218,10 @@ int main(void)
  bprint_pascal(&b, 25);
  printf("Long text count only buffer: %zu/%u\n", strlen(b.str), b.len);
 
+ av_bprint_init_for_buffer(&b, buf, sizeof(buf));
+ bprint_pascal(&b, 25);
+ printf("Long text count only buffer: %zu/%u\n", strlen(buf), b.len);
+
  return 0;
 }
 

libavutil/bprint.h

@@ -99,6 +99,17 @@ void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max);
 #define AV_BPRINT_SIZE_AUTOMATIC 1
 #define AV_BPRINT_SIZE_COUNT_ONLY 0
 
+/**
+ * Init a print buffer using a pre-existing buffer.
+ *
+ * The buffer will not be reallocated.
+ *
+ * @param buf buffer structure to init
+ * @param buffer byte buffer to use for the string data
+ * @param size size of buffer
+ */
+void av_bprint_init_for_buffer(AVBPrint *buf, char *buffer, unsigned size);
+
 /**
  * Append a formated string to a print buffer.
  */