diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/growing_fifo.c | 90 | ||||
| -rw-r--r-- | src/growing_fifo.h | 73 |
2 files changed, 163 insertions, 0 deletions
diff --git a/src/growing_fifo.c b/src/growing_fifo.c new file mode 100644 index 000000000..88431f60e --- /dev/null +++ b/src/growing_fifo.c @@ -0,0 +1,90 @@ +/* + * Copyright (C) 2003-2011 The Music Player Daemon Project + * http://www.musicpd.org + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +#include "growing_fifo.h" +#include "fifo_buffer.h" + +#include <assert.h> +#include <string.h> + +/** + * Align buffer sizes at 8 kB boundaries. Must be a power of two. + */ +static const size_t GROWING_FIFO_ALIGN = 8192; + +/** + * Align the specified size to the next #GROWING_FIFO_ALIGN boundary. + */ +static size_t +align(size_t size) +{ + return ((size - 1) | (GROWING_FIFO_ALIGN - 1)) + 1; +} + +struct fifo_buffer * +growing_fifo_new(void) +{ + return fifo_buffer_new(GROWING_FIFO_ALIGN); +} + +void * +growing_fifo_write(struct fifo_buffer **buffer_p, size_t length) +{ + assert(buffer_p != NULL); + + struct fifo_buffer *buffer = *buffer_p; + assert(buffer != NULL); + + size_t max_length; + void *p = fifo_buffer_write(buffer, &max_length); + if (p != NULL && max_length >= length) + return p; + + /* grow */ + size_t new_size = fifo_buffer_available(buffer) + length; + assert(new_size > fifo_buffer_capacity(buffer)); + *buffer_p = buffer = fifo_buffer_realloc(buffer, align(new_size)); + + /* try again */ + p = fifo_buffer_write(buffer, &max_length); + assert(p != NULL); + assert(max_length >= length); + + return p; +} + +void +growing_fifo_append(struct fifo_buffer **buffer_p, + const void *data, size_t length) +{ + void *p = growing_fifo_write(buffer_p, length); + memcpy(p, data, length); + fifo_buffer_append(*buffer_p, length); +} diff --git a/src/growing_fifo.h b/src/growing_fifo.h new file mode 100644 index 000000000..723c3b3ff --- /dev/null +++ b/src/growing_fifo.h @@ -0,0 +1,73 @@ +/* + * Copyright (C) 2003-2011 The Music Player Daemon Project + * http://www.musicpd.org + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * + * - Redistributions of source code must retain the above copyright + * notice, this list of conditions and the following disclaimer. + * + * - Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the + * distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS + * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT + * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS + * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE + * FOUNDATION OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES + * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR + * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) + * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, + * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) + * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED + * OF THE POSSIBILITY OF SUCH DAMAGE. + */ + +/** \file + * + * Helper functions for our FIFO buffer library (fifo_buffer.h) that + * allows growing the buffer on demand. + * + * This library is not thread safe. + */ + +#ifndef MPD_GROWING_FIFO_H +#define MPD_GROWING_FIFO_H + +#include <stddef.h> + +struct fifo_buffer; + +/** + * Allocate a new #fifo_buffer with the default size. + */ +struct fifo_buffer * +growing_fifo_new(void); + +/** + * Prepares writing to the buffer, see fifo_buffer_write() for + * details. The difference is that this function will automatically + * grow the buffer if it is too small. + * + * The caller is responsible for limiting the capacity of the buffer. + * + * @param length the number of bytes that will be written + * @return a pointer to the end of the buffer (will not be NULL) + */ +void * +growing_fifo_write(struct fifo_buffer **buffer_p, size_t length); + +/** + * A helper function that combines growing_fifo_write(), memcpy(), + * fifo_buffer_append(). + */ +void +growing_fifo_append(struct fifo_buffer **buffer_p, + const void *data, size_t length); + +#endif |