/*
 * A generic kernel FIFO implementation
 *
 * Copyright (C) 2009/2010 Stefani Seibold <stefani@seibold.net>
 *
 * 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.
 *
 */
#if 0
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/log2.h>
#include <linux/uaccess.h>
#include <linux/kfifo.h>
#endif

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

#include "fifo.h"

#define is_power_of_2(x)     ((x) != 0 && (((x) & ((x) - 1)) == 0))
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
#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; })
	
//#define	EINVAL				(1)
//#define ENOMEM				(2)

static inline int fls(int x);

#ifdef PLATFORM_R16
static inline int constant_fls(int x)
{
	int r = 32;

	if (!x)
		return 0;
	if (!(x & 0xffff0000u)) {
		x <<= 16;
		r -= 16;
	}
	if (!(x & 0xff000000u)) {
		x <<= 8;
		r -= 8;
	}
	if (!(x & 0xf0000000u)) {
		x <<= 4;
		r -= 4;
	}
	if (!(x & 0xc0000000u)) {
		x <<= 2;
		r -= 2;
	}
	if (!(x & 0x80000000u)) {
		x <<= 1;
		r -= 1;
	}
	return r;
}

static int fls64(unsigned long long x)
{
    unsigned int h = x >> 32;
    if (h)
        return fls(h) + 32;
    return fls(x);
}

static inline int fls(int x)
{                           
    int ret;                
                            
    if (__builtin_constant_p(x))
           return constant_fls(x);
                            
    asm("clz\t%0, %1" : "=r" (ret) : "r" (x));
        ret = 32 - ret;     
    return ret;             
}                  
#endif

#ifdef PLATFORM_CPU
#define __fls(x) (fls(x) - 1)
static __always_inline int fls64(unsigned long x)
{
    if (x == 0)
        return 0;
    return __fls(x) + 1;
}

static inline int fls(int x)
{                 
    int r;        
	
	long tmp = -1;
    asm("bsrl %1,%0"
        : "=r" (r)
        : "rm" (x), "0" (tmp));
#if 0
#ifdef CONFIG_X86_64
    /*            
     * AMD64 says BSRL won't clobber the dest reg if x==0; Intel64 says the
     * dest reg is undefined if x==0, but their CPU architect says its
     * value is written to set it to the same as before, except that the
     * top 32 bits will be cleared.
     *            
     * We cannot do this on 32 bits because at the very least some
     * 486 CPUs did not behave this way.
     */           
    long tmp = -1;
    asm("bsrl %1,%0"
        : "=r" (r)
        : "rm" (x), "0" (tmp));
#elif defined(CONFIG_X86_CMOV)
    asm("bsrl %1,%0\n\t"
        "cmovzl %2,%0"
        : "=&r" (r) : "rm" (x), "rm" (-1));
#else             
    asm("bsrl %1,%0\n\t"
        "jnz 1f\n\t"
        "movl $-1,%0\n"
        "1:" : "=r" (r) : "rm" (x));
#endif            
#endif
    return r + 1; 
}                 
#endif         
/*
 * internal helper to calculate the unused elements in a fifo
 */
static inline unsigned int kfifo_unused(struct __kfifo *fifo)
{
	return (fifo->mask + 1) - (fifo->in - fifo->out);
}

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

unsigned long roundup_pow_of_two(unsigned long n)
{   
    return 1UL << (fls_long(n));
}   

int __kfifo_alloc(struct __kfifo *fifo, unsigned int size, unsigned int esize)
{
	/*
	 * round down to the next power of 2, since our 'let the indices
	 * wrap' technique works only in this case.
	 */
	if (!is_power_of_2(size))
		size = roundup_pow_of_two(size);

	fprintf(stdout, "+++++++++++kfifo malloc size = %u\n", size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;

	if (size < 2) {
		fifo->data = NULL;
		fifo->mask = 0;
		return -EINVAL;
	}

	fifo->data = malloc(size * esize);

	if (!fifo->data) {
		fifo->mask = 0;
		return -ENOMEM;
	}
	fifo->mask = size - 1;
	uv_mutex_init(&fifo->lock);

	return 0;
}

void __kfifo_free(struct __kfifo *fifo)
{
	free(fifo->data);
	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = 0;
	fifo->data = NULL;
	fifo->mask = 0;
}

int __kfifo_init(struct __kfifo *fifo, void *buffer,
		unsigned int size, unsigned int esize)
{
	size /= esize;

	if (!is_power_of_2(size))
		size = roundup_pow_of_two(size);

	fifo->in = 0;
	fifo->out = 0;
	fifo->esize = esize;
	fifo->data = buffer;

	if (size < 2) {
		fifo->mask = 0;
		return -EINVAL;
	}
	fifo->mask = size - 1;
	uv_mutex_init(&fifo->lock);

	return 0;
}

static void kfifo_copy_in(struct __kfifo *fifo, const void *src,
		unsigned int len, unsigned int off)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	memcpy(fifo->data + off, src, l);
	memcpy(fifo->data, src + l, len - l);
	/*
	 * make sure that the data in the fifo is up to date before
	 * incrementing the fifo->in index counter
	 */
//	smp_wmb();
}

unsigned int __kfifo_in(struct __kfifo *fifo,
		const void *buf, unsigned int len)
{
	unsigned int l;

	l = kfifo_unused(fifo);
	if (len > l)
		len = l;

	kfifo_copy_in(fifo, buf, len, fifo->in);
	fifo->in += len;
	return len;
}

static void kfifo_copy_out(struct __kfifo *fifo, void *dst,
		unsigned int len, unsigned int off)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	if (dst) {
		memcpy(dst, fifo->data + off, l);
		memcpy(dst + l, fifo->data, len - l);
	}
	/*
	 * make sure that the data is copied before
	 * incrementing the fifo->out index counter
	 */
//	smp_wmb();
}

unsigned int __kfifo_out_peek(struct __kfifo *fifo,
		void *buf, unsigned int len)
{
	unsigned int l;

	l = fifo->in - fifo->out;
	if (len > l)
		len = l;

	kfifo_copy_out(fifo, buf, len, fifo->out);
	return len;
}

unsigned int __kfifo_out(struct __kfifo *fifo,
		void *buf, unsigned int len)
{
	len = __kfifo_out_peek(fifo, buf, len);
	fifo->out += len;
	return len;
}

#if 0
static unsigned long kfifo_copy_from_user(struct __kfifo *fifo,
	const void *from, unsigned int len, unsigned int off,
	unsigned int *copied)
{
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;
	unsigned int l;
	unsigned long ret;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	ret = memcpy(fifo->data + off, from, l);
	if (unlikely(ret))
		ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
		ret = memcpy(fifo->data, from + l, len - l);
		if (unlikely(ret))
			ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	 * make sure that the data in the fifo is up to date before
	 * incrementing the fifo->in index counter
	 */
//	smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
}

int __kfifo_from_user(struct __kfifo *fifo, const void __user *from,
		unsigned long len, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
		len /= esize;

	l = kfifo_unused(fifo);
	if (len > l)
		len = l;

	ret = kfifo_copy_from_user(fifo, from, len, fifo->in, copied);
	if (unlikely(ret)) {
		len -= ret;
		err = -EFAULT;
	} else
		err = 0;
	fifo->in += len;
	return err;
}

static unsigned long kfifo_copy_to_user(struct __kfifo *fifo, void __user *to,
		unsigned int len, unsigned int off, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int size = fifo->mask + 1;
	unsigned int esize = fifo->esize;

	off &= fifo->mask;
	if (esize != 1) {
		off *= esize;
		size *= esize;
		len *= esize;
	}
	l = min(len, size - off);

	ret = memcpy(to, fifo->data + off, l);
	if (unlikely(ret))
		ret = DIV_ROUND_UP(ret + len - l, esize);
	else {
		ret = memcpy(to + l, fifo->data, len - l);
		if (unlikely(ret))
			ret = DIV_ROUND_UP(ret, esize);
	}
	/*
	 * make sure that the data is copied before
	 * incrementing the fifo->out index counter
	 */
	//smp_wmb();
	*copied = len - ret;
	/* return the number of elements which are not copied */
	return ret;
}

int __kfifo_to_user(struct __kfifo *fifo, void __user *to,
		unsigned long len, unsigned int *copied)
{
	unsigned int l;
	unsigned long ret;
	unsigned int esize = fifo->esize;
	int err;

	if (esize != 1)
		len /= esize;

	l = fifo->in - fifo->out;
	if (len > l)
		len = l;
	ret = kfifo_copy_to_user(fifo, to, len, fifo->out, copied);
	if (unlikely(ret)) {
		len -= ret;
		err = -EFAULT;
	} else
		err = 0;
	fifo->out += len;
	return err;
}
#endif

unsigned int __kfifo_max_r(unsigned int len, unsigned int recsize)
{
	unsigned int max = (1 << (recsize << 3)) - 1;

	if (len > max)
		return max;
	return len;
}

#define	__KFIFO_PEEK(data, out, mask) \
	((data)[(out) & (mask)])
/*
 * __kfifo_peek_n internal helper function for determinate the length of
 * the next record in the fifo
 */
static unsigned int __kfifo_peek_n(struct __kfifo *fifo, unsigned int recsize)
{
	unsigned int l;
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	l = __KFIFO_PEEK(data, fifo->out, mask);

	if (--recsize)
		l |= __KFIFO_PEEK(data, fifo->out + 1, mask) << 8;

	return l;
}

#define	__KFIFO_POKE(data, in, mask, val) \
	( \
	(data)[(in) & (mask)] = (unsigned char)(val) \
	)

/*
 * __kfifo_poke_n internal helper function for storeing the length of
 * the record into the fifo
 */
static void __kfifo_poke_n(struct __kfifo *fifo, unsigned int n, unsigned int recsize)
{
	unsigned int mask = fifo->mask;
	unsigned char *data = fifo->data;

	__KFIFO_POKE(data, fifo->in, mask, n);

	if (recsize > 1)
		__KFIFO_POKE(data, fifo->in + 1, mask, n >> 8);
}

unsigned int __kfifo_len_r(struct __kfifo *fifo, unsigned int recsize)
{
	return __kfifo_peek_n(fifo, recsize);
}

unsigned int __kfifo_in_r(struct __kfifo *fifo, const void *buf,
		unsigned int len, unsigned int recsize)
{
	if (len + recsize > kfifo_unused(fifo))
		return 0;

	__kfifo_poke_n(fifo, len, recsize);

	kfifo_copy_in(fifo, buf, len, fifo->in + recsize);
	fifo->in += len + recsize;
	return len;
}

static unsigned int kfifo_out_copy_r(struct __kfifo *fifo,
	void *buf, unsigned int len, unsigned int recsize, unsigned int *n)
{
	*n = __kfifo_peek_n(fifo, recsize);

	if (len > *n)
		len = *n;

	kfifo_copy_out(fifo, buf, len, fifo->out + recsize);
	return len;
}

unsigned int __kfifo_out_peek_r(struct __kfifo *fifo, void *buf,
		unsigned int len, unsigned int recsize)
{
	unsigned int n;

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

	return kfifo_out_copy_r(fifo, buf, len, recsize, &n);
}

unsigned int __kfifo_out_r(struct __kfifo *fifo, void *buf,
		unsigned int len, unsigned int recsize)
{
	unsigned int n;

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

	len = kfifo_out_copy_r(fifo, buf, len, recsize, &n);
	fifo->out += n + recsize;
	return len;
}

void __kfifo_skip_r(struct __kfifo *fifo, unsigned int recsize)
{
	unsigned int n;

	n = __kfifo_peek_n(fifo, recsize);
	fifo->out += n + recsize;
}