kfifo.h

LInux BootLoader的说明文档

#ifndef _LINUX_KFIFO_H
#define _LINUX_KFIFO_H

#define __u32 unsigned long
#define __u64 unsigned long long

#define min(x,y) ({ \
        typeof(x) _x = (x);     \
        typeof(y) _y = (y);     \
        (void) (&_x == &_y);            \
        _x < _y ? _x : _y; })

#define max(x,y) ({ \
        typeof(x) _x = (x);     \
        typeof(y) _y = (y);     \
        (void) (&_x == &_y);            \
        _x > _y ? _x : _y; })

static inline int fls(int x)
{
    int r;

    __asm__("bsrl %1,%0\n\t"
            "jnz 1f\n\t"
            "movl $-1,%0\n"
            "1:" : "=r" (r) : "rm" (x));
    return r+1;
}

static inline int fls64(__u64 x)
{
    __u32 h = x >> 32;
    if (h)
        return fls(h) + 32;
    return fls(x);
}

static inline unsigned fls_long(unsigned long l)
{
    if (sizeof(l) == 4)
        return fls(l);
    return fls64(l);
}

static inline unsigned long roundup_pow_of_two(unsigned long x)
{
    return 1UL << fls_long(x - 1);
}

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);
unsigned int __kfifo_put(struct kfifo *fifo, unsigned char *buffer, unsigned int len);
unsigned int __kfifo_get(struct kfifo *fifo, unsigned char *buffer, unsigned int len);

static inline void __kfifo_reset(struct kfifo *fifo)
{
    fifo->in = fifo->out = 0;
}

static inline void kfifo_reset(struct kfifo *fifo)
{

    __kfifo_reset(fifo);

}

static inline unsigned int kfifo_put(struct kfifo *fifo,
                     unsigned char *buffer, unsigned int len)
{
    unsigned int ret;

    ret = __kfifo_put(fifo, buffer, len);

    return ret;
}

static inline unsigned int kfifo_get(struct kfifo *fifo,
                     unsigned char *buffer, unsigned int len)
{
    unsigned int ret;

    ret = __kfifo_get(fifo, buffer, len);

    if (fifo->in == fifo->out)
        fifo->in = fifo->out = 0;


    return ret;
}

static inline unsigned int __kfifo_len(struct kfifo *fifo)
{
    return fifo->in - fifo->out;
}

static inline unsigned int kfifo_len(struct kfifo *fifo)
{
    unsigned int ret;

    ret = __kfifo_len(fifo);

    return ret;
}

#endif