From 90a17da95cc5dc558cee9446e75b2daa84212be3 Mon Sep 17 00:00:00 2001 From: Sascha Hauer Date: Fri, 21 Sep 2007 21:29:32 +0200 Subject: [PATCH] add kernel kfifo implementation --- include/kfifo.h | 83 ++++++++++++++++++++++++ lib/Makefile | 1 + lib/kfifo.c | 166 ++++++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 250 insertions(+) create mode 100644 include/kfifo.h create mode 100644 lib/kfifo.c diff --git a/include/kfifo.h b/include/kfifo.h new file mode 100644 index 000000000..6f8be10f6 --- /dev/null +++ b/include/kfifo.h @@ -0,0 +1,83 @@ +/* + * A simple kernel FIFO implementation. + * + * Copyright (C) 2004 Stelian Pop + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + */ +#ifndef _LINUX_KFIFO_H +#define _LINUX_KFIFO_H + +struct kfifo { + unsigned char *buffer; /* the buffer holding the data */ + unsigned int size; /* the size of the allocated buffer */ + unsigned int in; /* data is added at offset (in % size) */ + unsigned int out; /* data is extracted from off. (out % size) */ +}; + +struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size); +struct kfifo *kfifo_alloc(unsigned int size); +void kfifo_free(struct kfifo *fifo); + +/** + * kfifo_put - puts some data into the FIFO + * @fifo: the fifo to be used. + * @buffer: the data to be added. + * @len: the length of the data to be added. + * + * This function copies at most @len bytes from the @buffer into + * the FIFO depending on the free space, and returns the number of + * bytes copied. + */ +unsigned int kfifo_put(struct kfifo *fifo, + unsigned char *buffer, unsigned int len); + +/** + * kfifo_get - gets some data from the FIFO + * @fifo: the fifo to be used. + * @buffer: where the data must be copied. + * @len: the size of the destination buffer. + * + * This function copies at most @len bytes from the FIFO into the + * @buffer and returns the number of copied bytes. + */ +unsigned int kfifo_get(struct kfifo *fifo, + unsigned char *buffer, unsigned int len); + +/** + * kfifo_reset - removes the entire FIFO contents + * @fifo: the fifo to be emptied. + */ +static inline void kfifo_reset(struct kfifo *fifo) +{ + fifo->in = fifo->out = 0; +} + + +/** + * kfifo_len - returns the number of bytes available in the FIFO. + * @fifo: the fifo to be used. + */ +static inline unsigned int kfifo_len(struct kfifo *fifo) +{ + return fifo->in - fifo->out; +} + +void kfifo_putc(struct kfifo *fifo, unsigned char c); +unsigned int kfifo_getc(struct kfifo *fifo, unsigned char *c); + +#endif + diff --git a/lib/Makefile b/lib/Makefile index 0aaf53f69..04c62b17b 100644 --- a/lib/Makefile +++ b/lib/Makefile @@ -10,6 +10,7 @@ obj-y += parameter.o obj-y += xfuncs.o obj-y += getopt.o obj-y += readkey.o +obj-y += kfifo.o obj-$(CONFIG_BZLIB) += bzlib.o bzlib_crctable.o bzlib_decompress.o bzlib_huffman.o bzlib_randtable.o obj-$(CONFIG_ZLIB) += zlib.o gunzip.o obj-$(CONFIG_CRC32) += crc32.o diff --git a/lib/kfifo.c b/lib/kfifo.c new file mode 100644 index 000000000..bf5cee1de --- /dev/null +++ b/lib/kfifo.c @@ -0,0 +1,166 @@ +/* + * A simple kernel FIFO implementation. + * + * Copyright (C) 2004 Stelian Pop + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program 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 General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, write to the Free Software + * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. + * + */ + +#include +#include +#include +#include + +/** + * kfifo_init - allocates a new FIFO using a preallocated buffer + * @buffer: the preallocated buffer to be used. + * @size: the size of the internal buffer, this have to be a power of 2. + * @gfp_mask: get_free_pages mask, passed to kmalloc() + * @lock: the lock to be used to protect the fifo buffer + * + * Do NOT pass the kfifo to kfifo_free() after use! Simply free the + * &struct kfifo with free(). + */ +struct kfifo *kfifo_init(unsigned char *buffer, unsigned int size) +{ + struct kfifo *fifo; + + fifo = malloc(sizeof(struct kfifo)); + if (!fifo) + return NULL; + + fifo->buffer = buffer; + fifo->size = size; + fifo->in = fifo->out = 0; + + return fifo; +} + +/** + * kfifo_alloc - allocates a new FIFO and its internal buffer + * @size: the size of the internal buffer to be allocated. + * @gfp_mask: get_free_pages mask, passed to kmalloc() + * @lock: the lock to be used to protect the fifo buffer + * + * The size will be rounded-up to a power of 2. + */ +struct kfifo *kfifo_alloc(unsigned int size) +{ + unsigned char *buffer; + struct kfifo *ret; + + buffer = malloc(size); + if (!buffer) + return NULL; + + ret = kfifo_init(buffer, size); + + if (!ret) + free(buffer); + + return ret; +} + +/** + * kfifo_free - frees the FIFO + * @fifo: the fifo to be freed. + */ +void kfifo_free(struct kfifo *fifo) +{ + free(fifo->buffer); + free(fifo); +} + +/** + * kfifo_put - puts some data into the FIFO, no locking version + * @fifo: the fifo to be used. + * @buffer: the data to be added. + * @len: the length of the data to be added. + * + * This function copies at most @len bytes from the @buffer into + * the FIFO depending on the free space, and returns the number of + * bytes copied. + * + */ +unsigned int kfifo_put(struct kfifo *fifo, + unsigned char *buffer, unsigned int len) +{ + unsigned int l; + + len = min(len, fifo->size - fifo->in + fifo->out); + + /* first put the data starting from fifo->in to buffer end */ + l = min(len, fifo->size - (fifo->in & (fifo->size - 1))); + memcpy(fifo->buffer + (fifo->in & (fifo->size - 1)), buffer, l); + + /* then put the rest (if any) at the beginning of the buffer */ + memcpy(fifo->buffer, buffer + l, len - l); + + fifo->in += len; + + return len; +} + +/** + * kfifo_get - gets some data from the FIFO, no locking version + * @fifo: the fifo to be used. + * @buffer: where the data must be copied. + * @len: the size of the destination buffer. + * + * This function copies at most @len bytes from the FIFO into the + * @buffer and returns the number of copied bytes. + * + * Note that with only one concurrent reader and one concurrent + * writer, you don't need extra locking to use these functions. + */ +unsigned int kfifo_get(struct kfifo *fifo, + unsigned char *buffer, unsigned int len) +{ + unsigned int l; + + len = min(len, fifo->in - fifo->out); + + /* first get the data from fifo->out until the end of the buffer */ + l = min(len, fifo->size - (fifo->out & (fifo->size - 1))); + memcpy(buffer, fifo->buffer + (fifo->out & (fifo->size - 1)), l); + + /* then get the rest (if any) from the beginning of the buffer */ + memcpy(buffer + l, fifo->buffer, len - l); + + fifo->out += len; + + return len; +} + +void kfifo_putc(struct kfifo *fifo, unsigned char c) +{ + *(fifo->buffer + (fifo->in & (fifo->size - 1))) = c; + fifo->in++; + if (fifo->in - fifo->out > fifo->size) + fifo->out++; +} + +unsigned int kfifo_getc(struct kfifo *fifo, unsigned char *c) +{ + if (fifo->in == fifo->out) + return -1; + + *c = *(fifo->buffer + (fifo->out & (fifo->size - 1))); + fifo->out++; + + return 0; +} +