/**************************************************************************
*
* Copyright 2011 Christian König.
* All Rights Reserved.
*
* Permission is hereby granted, free of charge, to any person obtaining a
* copy of this software and associated documentation files (the
* "Software"), to deal in the Software without restriction, including
* without limitation the rights to use, copy, modify, merge, publish,
* distribute, sub license, and/or sell copies of the Software, and to
* permit persons to whom the Software is furnished to do so, subject to
* the following conditions:
*
* The above copyright notice and this permission notice (including the
* next paragraph) shall be included in all copies or substantial portions
* of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
* IN NO EVENT SHALL VMWARE AND/OR ITS SUPPLIERS BE LIABLE FOR
* ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
* TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
* SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
*
**************************************************************************/
/*
* Functions for fast bitwise access to multiple probably unaligned input buffers
*/
#ifndef vl_vlc_h
#define vl_vlc_h
#include "pipe/p_compiler.h"
#include "util/u_math.h"
#include "util/u_pointer.h"
#include "util/u_debug.h"
struct vl_vlc
{
uint64_t buffer;
signed invalid_bits;
const uint8_t *data;
const uint8_t *end;
const void *const *inputs;
const unsigned *sizes;
unsigned bytes_left;
};
struct vl_vlc_entry
{
int8_t length;
int8_t value;
};
struct vl_vlc_compressed
{
uint16_t bitcode;
struct vl_vlc_entry entry;
};
/**
* initalize and decompress a lookup table
*/
static INLINE void
vl_vlc_init_table(struct vl_vlc_entry *dst, unsigned dst_size, const struct vl_vlc_compressed *src, unsigned src_size)
{
unsigned i, bits = util_logbase2(dst_size);
assert(dst && dst_size);
assert(src && src_size);
for (i=0;i<dst_size;++i) {
dst[i].length = 0;
dst[i].value = 0;
}
for(; src_size > 0; --src_size, ++src) {
for(i=0; i<(1 << (bits - src->entry.length)); ++i)
dst[src->bitcode >> (16 - bits) | i] = src->entry;
}
}
/**
* switch over to next input buffer
*/
static INLINE void
vl_vlc_next_input(struct vl_vlc *vlc)
{
unsigned len = vlc->sizes[0];
assert(vlc);
assert(vlc->bytes_left);
if (len < vlc->bytes_left)
vlc->bytes_left -= len;
else {
len = vlc->bytes_left;
vlc->bytes_left = 0;
}
vlc->data = vlc->inputs[0];
vlc->end = vlc->data + len;
++vlc->inputs;
++vlc->sizes;
}
/**
* align the data pointer to the next dword
*/
static INLINE void
vl_vlc_align_data_ptr(struct vl_vlc *vlc)
{
/* align the data pointer */
while (vlc->data != vlc->end && pointer_to_uintptr(vlc->data) & 3) {
vlc->buffer |= (uint64_t)*vlc->data << (24 + vlc->invalid_bits);
++vlc->data;
vlc->invalid_bits -= 8;
}
}
/**
* fill the bit buffer, so that at least 32 bits are valid
*/
static INLINE void
vl_vlc_fillbits(struct vl_vlc *vlc)
{
assert(vlc);
/* as long as the buffer needs to be filled */
while (vlc->invalid_bits > 0) {
unsigned bytes_left = vlc->end - vlc->data;
/* if this input is depleted */
if (bytes_left == 0) {
if (vlc->bytes_left) {
/* go on to next input */
vl_vlc_next_input(vlc);
vl_vlc_align_data_ptr(vlc);
} else
/* or give up since we don't have anymore inputs */
return;
} else if (bytes_left >= 4) {
/* enough bytes in buffer, read in a whole dword */
uint64_t value = *(const uint32_t*)vlc->data;
#ifndef PIPE_ARCH_BIG_ENDIAN
value = util_bswap32(value);
#endif
vlc->buffer |= value << vlc->invalid_bits;
vlc->data += 4;
vlc->invalid_bits -= 32;
/* buffer is now definitely filled up avoid the loop test */
break;
} else while (vlc->data < vlc->end) {
/* not enough bytes left in buffer, read single bytes */
vlc->buffer |= (uint64_t)*vlc->data << (24 + vlc->invalid_bits);
++vlc->data;
vlc->invalid_bits -= 8;
}
}
}
/**
* initialize vlc structure and start reading from first input buffer
*/
static INLINE void
vl_vlc_init(struct vl_vlc *vlc, unsigned num_inputs,
const void *const *inputs, const unsigned *sizes)
{
unsigned i;
assert(vlc);
assert(num_inputs);
vlc->buffer = 0;
vlc->invalid_bits = 32;
vlc->inputs = inputs;
vlc->sizes = sizes;
vlc->bytes_left = 0;
for (i = 0; i < num_inputs; ++i)
vlc->bytes_left += sizes[i];
if (vlc->bytes_left) {
vl_vlc_next_input(vlc);
vl_vlc_align_data_ptr(vlc);
vl_vlc_fillbits(vlc);
}
}
/**
* number of bits still valid in bit buffer
*/
static INLINE unsigned
vl_vlc_valid_bits(struct vl_vlc *vlc)
{
return 32 - vlc->invalid_bits;
}
/**
* number of bits left over all inbut buffers
*/
static INLINE unsigned
vl_vlc_bits_left(struct vl_vlc *vlc)
{
signed bytes_left = vlc->end - vlc->data;
bytes_left += vlc->bytes_left;
return bytes_left * 8 + vl_vlc_valid_bits(vlc);
}
/**
* get num_bits from bit buffer without removing them
*/
static INLINE unsigned
vl_vlc_peekbits(struct vl_vlc *vlc, unsigned num_bits)
{
assert(vl_vlc_valid_bits(vlc) >= num_bits || vlc->data >= vlc->end);
return vlc->buffer >> (64 - num_bits);
}
/**
* remove num_bits from bit buffer
*/
static INLINE void
vl_vlc_eatbits(struct vl_vlc *vlc, unsigned num_bits)
{
assert(vl_vlc_valid_bits(vlc) >= num_bits);
vlc->buffer <<= num_bits;
vlc->invalid_bits += num_bits;
}
/**
* get num_bits from bit buffer with removing them
*/
static INLINE unsigned
vl_vlc_get_uimsbf(struct vl_vlc *vlc, unsigned num_bits)
{
unsigned value;
assert(vl_vlc_valid_bits(vlc) >= num_bits);
value = vlc->buffer >> (64 - num_bits);
vl_vlc_eatbits(vlc, num_bits);
return value;
}
/**
* treat num_bits as signed value and remove them from bit buffer
*/
static INLINE signed
vl_vlc_get_simsbf(struct vl_vlc *vlc, unsigned num_bits)
{
signed value;
assert(vl_vlc_valid_bits(vlc) >= num_bits);
value = ((int64_t)vlc->buffer) >> (64 - num_bits);
vl_vlc_eatbits(vlc, num_bits);
return value;
}
/**
* lookup a value and length in a decompressed table
*/
static INLINE int8_t
vl_vlc_get_vlclbf(struct vl_vlc *vlc, const struct vl_vlc_entry *tbl, unsigned num_bits)
{
tbl += vl_vlc_peekbits(vlc, num_bits);
vl_vlc_eatbits(vlc, tbl->length);
return tbl->value;
}
/**
* fast forward search for a specific byte value
*/
static INLINE boolean
vl_vlc_search_byte(struct vl_vlc *vlc, unsigned num_bits, uint8_t value)
{
/* make sure we are on a byte boundary */
assert((vl_vlc_valid_bits(vlc) % 8) == 0);
assert(num_bits == ~0 || (num_bits % 8) == 0);
/* deplete the bit buffer */
while (vl_vlc_valid_bits(vlc) > 0) {
if (vl_vlc_peekbits(vlc, 8) == value) {
vl_vlc_fillbits(vlc);
return TRUE;
}
vl_vlc_eatbits(vlc, 8);
if (num_bits != ~0) {
num_bits -= 8;
if (num_bits == 0)
return FALSE;
}
}
/* deplete the byte buffers */
while (1) {
/* if this input is depleted */
if (vlc->data == vlc->end) {
if (vlc->bytes_left)
/* go on to next input */
vl_vlc_next_input(vlc);
else
/* or give up since we don't have anymore inputs */
return FALSE;
}
if (*vlc->data == value) {
vl_vlc_align_data_ptr(vlc);
vl_vlc_fillbits(vlc);
return TRUE;
}
++vlc->data;
if (num_bits != ~0) {
num_bits -= 8;
if (num_bits == 0) {
vl_vlc_align_data_ptr(vlc);
return FALSE;
}
}
}
}
/**
* remove num_bits bits starting at pos from the bitbuffer
*/
static INLINE void
vl_vlc_removebits(struct vl_vlc *vlc, unsigned pos, unsigned num_bits)
{
uint64_t lo = (vlc->buffer & (~0UL >> (pos + num_bits))) << num_bits;
uint64_t hi = (vlc->buffer & (~0UL << (64 - pos)));
vlc->buffer = lo | hi;
vlc->invalid_bits += num_bits;
}
/**
* limit the number of bits left for fetching
*/
static INLINE void
vl_vlc_limit(struct vl_vlc *vlc, unsigned bits_left)
{
assert(bits_left <= vl_vlc_bits_left(vlc));
vl_vlc_fillbits(vlc);
if (bits_left < vl_vlc_valid_bits(vlc)) {
vlc->invalid_bits = 32 - bits_left;
vlc->buffer &= ~0L << (vlc->invalid_bits + 32);
vlc->end = vlc->data;
vlc->bytes_left = 0;
} else {
assert((bits_left - vl_vlc_valid_bits(vlc)) % 8 == 0);
vlc->bytes_left = (bits_left - vl_vlc_valid_bits(vlc)) / 8;
if (vlc->bytes_left < (vlc->end - vlc->data)) {
vlc->end = vlc->data + vlc->bytes_left;
vlc->bytes_left = 0;
} else
vlc->bytes_left -= vlc->end - vlc->data;
}
}
#endif /* vl_vlc_h */