FFmpeg
1.2.12
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Data Structures | |
struct | AVBPrint |
Buffer to print data progressively. More... |
Macros | |
#define | FF_PAD_STRUCTURE(size,...) |
Define a structure with extra padding to a fixed size This helps ensuring binary compatibility with future versions. | |
#define | AV_BPRINT_SIZE_UNLIMITED ((unsigned)-1) |
Convenience macros for special values for av_bprint_init() size_max parameter. | |
#define | AV_BPRINT_SIZE_AUTOMATIC 1 |
#define | AV_BPRINT_SIZE_COUNT_ONLY 0 |
Typedefs | |
typedef struct AVBPrint | AVBPrint |
Buffer to print data progressively. |
Functions | |
void | av_bprint_init (AVBPrint *buf, unsigned size_init, unsigned size_max) |
Init a print buffer. | |
void | av_bprint_init_for_buffer (AVBPrint *buf, char *buffer, unsigned size) |
Init a print buffer using a pre-existing buffer. | |
void | av_bprintf (AVBPrint *buf, const char *fmt,...) av_printf_format(2 |
Append a formatted string to a print buffer. | |
void void | av_bprint_chars (AVBPrint *buf, char c, unsigned n) |
Append char c n times to a print buffer. | |
void | av_bprint_strftime (AVBPrint *buf, const char *fmt, const struct tm *tm) |
Append a formatted date and time to a print buffer. | |
void | av_bprint_get_buffer (AVBPrint *buf, unsigned size, unsigned char **mem, unsigned *actual_size) |
Allocate bytes in the buffer for external use. | |
void | av_bprint_clear (AVBPrint *buf) |
Reset the string to "" but keep internal allocated data. | |
static int | av_bprint_is_complete (AVBPrint *buf) |
Test if the print buffer is complete (not truncated). | |
int | av_bprint_finalize (AVBPrint *buf, char **ret_str) |
Finalize a print buffer. | |
void | av_bprint_escape (AVBPrint *dstbuf, const char *src, const char *special_chars, enum AVEscapeMode mode, int flags) |
Escape the content in src and append it to dstbuf. |
#define AV_BPRINT_SIZE_UNLIMITED ((unsigned)-1) |
Convenience macros for special values for av_bprint_init() size_max parameter.
#define FF_PAD_STRUCTURE | ( | size, | |
... | |||
) |
Buffer to print data progressively.
The string buffer grows as necessary and is always 0-terminated. The content of the string is never accessed, and thus is encoding-agnostic and can even hold binary data.
Small buffers are kept in the structure itself, and thus require no memory allocation at all (unless the contents of the buffer is needed after the structure goes out of scope). This is almost as lightweight as declaring a local "char buf[512]".
The length of the string can go beyond the allocated size: the buffer is then truncated, but the functions still keep account of the actual total length.
In other words, buf->len can be greater than buf->size and records the total length of what would have been to the buffer if there had been enough memory.
Append operations do not need to be tested for failure: if a memory allocation fails, data stop being appended to the buffer, but the length is still updated. This situation can be tested with av_bprint_is_complete().
The size_max field determines several possible behaviours:
size_max = -1 (= UINT_MAX) or any large value will let the buffer be reallocated as necessary, with an amortized linear cost.
size_max = 0 prevents writing anything to the buffer: only the total length is computed. The write operations can then possibly be repeated in a buffer with exactly the necessary size (using size_init = size_max = len + 1).
size_max = 1 is automatically replaced by the exact size available in the structure itself, thus ensuring no dynamic memory allocation. The internal buffer is large enough to hold a reasonable paragraph of text, such as the current paragraph.
void av_bprint_escape | ( | AVBPrint * | dstbuf, |
const char * | src, | ||
const char * | special_chars, | ||
enum AVEscapeMode | mode, | ||
int | flags | ||
) |
Escape the content in src and append it to dstbuf.
dstbuf | already inited destination bprint buffer |
src | string containing the text to escape |
special_chars | string containing the special characters which need to be escaped, can be NULL |
mode | escape mode to employ, see AV_ESCAPE_MODE_* macros. Any unknown value for mode will be considered equivalent to AV_ESCAPE_MODE_BACKSLASH, but this behaviour can change without notice. |
flags | flags which control how to escape, see AV_ESCAPE_FLAG_* macros |
int av_bprint_finalize | ( | AVBPrint * | buf, |
char ** | ret_str | ||
) |
Finalize a print buffer.
The print buffer can no longer be used afterwards, but the len and size fields are still valid.
Init a print buffer.
buf | buffer to init |
size_init | initial size (including the final 0) |
size_max | maximum size; 0 means do not write anything, just count the length; 1 is replaced by the maximum value for automatic storage; any large value means that the internal buffer will be reallocated as needed up to that limit; -1 is converted to UINT_MAX, the largest limit possible. Check also AV_BPRINT_SIZE_* macros. |
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inlinestatic |
Append a formatted date and time to a print buffer.
param buf bprint buffer to use param fmt date and time format string, see strftime() param tm broken-down time structure to translate