[FFmpeg-devel] [PATCH] lavu: add av_bprintf and related.
Nicolas George
nicolas.george at normalesup.org
Wed Feb 22 22:19:55 CET 2012
Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---
doc/APIchanges | 3 +
libavutil/Makefile | 2 +
libavutil/avutil.h | 2 +-
libavutil/bprint.c | 135 ++++++++++++++++++++++++++++++++++++++++++++++++++++
libavutil/bprint.h | 120 ++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 261 insertions(+), 1 deletions(-)
create mode 100644 libavutil/bprint.c
create mode 100644 libavutil/bprint.h
diff --git a/doc/APIchanges b/doc/APIchanges
index 6c24501..990fec4 100644
--- a/doc/APIchanges
+++ b/doc/APIchanges
@@ -13,6 +13,9 @@ libavutil: 2011-04-18
API changes, most recent first:
+2012-02-22 - xxxxxxx - lavu 51.41.100
+ Add bprint.h for bprint API.
+
2012-02-21 - xxxxxxx - lavc 54.4.100
Add av_get_pcm_codec() function.
diff --git a/libavutil/Makefile b/libavutil/Makefile
index 6d78bd5..ac3eed0 100644
--- a/libavutil/Makefile
+++ b/libavutil/Makefile
@@ -10,6 +10,7 @@ HEADERS = adler32.h \
avstring.h \
avutil.h \
base64.h \
+ bprint.h \
bswap.h \
common.h \
cpu.h \
@@ -47,6 +48,7 @@ OBJS = adler32.o \
audioconvert.o \
avstring.o \
base64.o \
+ bprint.o \
cpu.o \
crc.o \
des.o \
diff --git a/libavutil/avutil.h b/libavutil/avutil.h
index 1b09407..fdd6cf1 100644
--- a/libavutil/avutil.h
+++ b/libavutil/avutil.h
@@ -154,7 +154,7 @@
*/
#define LIBAVUTIL_VERSION_MAJOR 51
-#define LIBAVUTIL_VERSION_MINOR 40
+#define LIBAVUTIL_VERSION_MINOR 41
#define LIBAVUTIL_VERSION_MICRO 100
#define LIBAVUTIL_VERSION_INT AV_VERSION_INT(LIBAVUTIL_VERSION_MAJOR, \
diff --git a/libavutil/bprint.c b/libavutil/bprint.c
new file mode 100644
index 0000000..69a8f8f
--- /dev/null
+++ b/libavutil/bprint.c
@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2012 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include <stdarg.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <string.h>
+#include "bprint.h"
+#include "common.h"
+#include "error.h"
+#include "mem.h"
+
+#define av_bprint_room(buf) ((buf)->size - FFMIN((buf)->len, (buf)->size))
+#define av_bprint_is_allocated(buf) ((buf)->str != (buf)->reserved_internal_buffer)
+
+static int av_bprint_grow(AVBPrint *buf, unsigned new_size)
+{
+ char *old_str, *new_str;
+
+ if (buf->size == buf->size_max)
+ return AVERROR(EIO);
+ if (!av_bprint_is_complete(buf))
+ return AVERROR_INVALIDDATA; /* it is already truncated anyway */
+ if (!new_size)
+ new_size = buf->size > buf->size_max / 2 ? buf->size_max :
+ buf->size * 2;
+ old_str = av_bprint_is_allocated(buf) ? buf->str : NULL;
+ new_str = av_realloc(old_str, new_size);
+ if (!new_str)
+ return AVERROR(ENOMEM);
+ if (!old_str)
+ memcpy(new_str, buf->str, buf->len + 1);
+ buf->str = new_str;
+ buf->size = new_size;
+ return 0;
+}
+
+void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max)
+{
+ unsigned asize = (char *)buf + sizeof(*buf) - buf->reserved_internal_buffer;
+
+ if (size_max == 1)
+ size_max = asize;
+ buf->str = buf->reserved_internal_buffer;
+ buf->len = 0;
+ buf->size = FFMIN(asize, size_max);
+ buf->size_max = size_max;
+ *buf->str = 0;
+ if (size_init > buf->size)
+ av_bprint_grow(buf, size_init);
+}
+
+void av_bprintf(AVBPrint *buf, const char *fmt, ...)
+{
+ unsigned room;
+ char *dst;
+ va_list vl;
+ int add;
+
+ while (1) {
+ room = av_bprint_room(buf);
+ dst = room ? buf->str + buf->len : NULL;
+ va_start(vl, fmt);
+ add = vsnprintf(dst, room, fmt, vl);
+ va_end(vl);
+ if (add <= 0)
+ return;
+ if (add < room)
+ break;
+ if (av_bprint_grow(buf, 0))
+ break;
+ }
+ add = FFMIN(add, UINT_MAX - 5 - buf->len);
+ buf->len += add;
+}
+
+void av_bprint_chars(AVBPrint *buf, char c, unsigned n)
+{
+ unsigned room, real_n;
+
+ while (1) {
+ room = av_bprint_room(buf);
+ if (n < room)
+ break;
+ if (av_bprint_grow(buf, 0))
+ break;
+ }
+ if (room) {
+ real_n = FFMIN(n, room - 1);
+ memset(buf->str + buf->len, c, real_n);
+ buf->str[buf->len + real_n] = 0;
+ }
+ buf->len += FFMIN(n, UINT_MAX - 5 - buf->len);
+}
+
+void av_bprint_finalize(AVBPrint *buf, char **ret_str)
+{
+ unsigned real_size = FFMIN(buf->len + 1, buf->size);
+ char *str;
+
+ if (ret_str) {
+ if (av_bprint_is_allocated(buf)) {
+ str = av_realloc(buf->str, real_size);
+ if (!str)
+ str = buf->str;
+ buf->str = NULL;
+ } else {
+ str = av_malloc(real_size);
+ if (str)
+ memcpy(str, buf->str, real_size);
+ }
+ *ret_str = str;
+ } else {
+ if (av_bprint_is_allocated(buf))
+ av_freep(&buf->str);
+ }
+ buf->size = real_size;
+}
diff --git a/libavutil/bprint.h b/libavutil/bprint.h
new file mode 100644
index 0000000..7303435
--- /dev/null
+++ b/libavutil/bprint.h
@@ -0,0 +1,120 @@
+/*
+ * Copyright (c) 2012 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_BPRINT_H
+#define AVUTIL_BPRINT_H
+
+#include "attributes.h"
+
+/**
+ * Define a structure with extra padding to a fixed size
+ * This helps ensuring binary compatibility with future versions.
+ */
+#define FF_PAD_STRUCTURE(size, ...) \
+ __VA_ARGS__ \
+ char reserved_padding[size - sizeof(struct { __VA_ARGS__ })];
+
+/**
+ * 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.
+ *
+ * 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.
+ */
+typedef struct AVBPrint {
+ FF_PAD_STRUCTURE(1024,
+ char *str; /** string so far; or NULL if size == 0 */
+ unsigned len; /** length so far */
+ unsigned size; /** allocated memory */
+ unsigned size_max; /** maximum allocated memory */
+ char reserved_internal_buffer[1];
+ )
+} AVBPrint;
+
+/**
+ * Init a print buffer
+ * @param buf buffer to init
+ * @param size_init initial size (including the final 0)
+ * @param size_max maximum size;
+ * 0 means do not write anything, just count the length;
+ * 1 is replaced by the maximum value for automatic storage
+ */
+void av_bprint_init(AVBPrint *buf, unsigned size_init, unsigned size_max);
+
+/**
+ * Append a formated string to a print buffer
+ */
+void av_bprintf(AVBPrint *buf, const char *fmt, ...) av_printf_format(2, 3);
+
+/**
+ * Append n times char c to a print buffer
+ */
+void av_bprint_chars(AVBPrint *buf, char c, unsigned n);
+
+/**
+ * Tests if the print buffer is complete
+ * It may have been truncated due to a memory allocation failure
+ * or the size_max limit (compare size and size_max if necessary).
+ */
+static inline int av_bprint_is_complete(AVBPrint *buf)
+{
+ return buf->len < buf->size;
+}
+
+/**
+ * Finalize a print buffer
+ * The print buffer can no longer be used afterwards,
+ * but the len and size fields are still valid.
+ * @arg[out] ret_str if not NULL, used to return a permanent copy of the
+ * buffer contents, or NULL if memory allocation fails;
+ * if NULL, the buffer is discarded and freed
+ */
+void av_bprint_finalize(AVBPrint *buf, char **ret_str);
+
+#endif /* AVUTIL_BPRINT_H */
--
1.7.9
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