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/*
* Copyright (c) 2010 The VP8 project authors. All Rights Reserved.
*
* Use of this source code is governed by a BSD-style license and patent
* grant that can be found in the LICENSE file in the root of the source
* tree. All contributing project authors may be found in the AUTHORS
* file in the root of the source tree.
*/
/****************************************************************************
* Notes:
*
* This implementation makes use of 16 bit fixed point verio of two multiply
* constants:
* 1. sqrt(2) * cos (pi/8)
* 2. sqrt(2) * sin (pi/8)
* Becuase the first constant is bigger than 1, to maintain the same 16 bit
* fixed point precision as the second one, we use a trick of
* x * a = x + x*(a-1)
* so
* x * sqrt(2) * cos (pi/8) = x + x * (sqrt(2) *cos(pi/8)-1).
**************************************************************************/
static const int cospi8sqrt2minus1 = 20091;
static const int sinpi8sqrt2 = 35468;
static const int rounding = 0;
void vp8_short_idct4x4llm_c(short *input, short *output, int pitch)
{
int i;
int a1, b1, c1, d1;
short *ip = input;
short *op = output;
int temp1, temp2;
int shortpitch = pitch >> 1;
for (i = 0; i < 4; i++)
{
a1 = ip[0] + ip[8];
b1 = ip[0] - ip[8];
temp1 = (ip[4] * sinpi8sqrt2 + rounding) >> 16;
temp2 = ip[12] + ((ip[12] * cospi8sqrt2minus1 + rounding) >> 16);
c1 = temp1 - temp2;
temp1 = ip[4] + ((ip[4] * cospi8sqrt2minus1 + rounding) >> 16);
temp2 = (ip[12] * sinpi8sqrt2 + rounding) >> 16;
d1 = temp1 + temp2;
op[shortpitch*0] = a1 + d1;
op[shortpitch*3] = a1 - d1;
op[shortpitch*1] = b1 + c1;
op[shortpitch*2] = b1 - c1;
ip++;
op++;
}
ip = output;
op = output;
for (i = 0; i < 4; i++)
{
a1 = ip[0] + ip[2];
b1 = ip[0] - ip[2];
temp1 = (ip[1] * sinpi8sqrt2 + rounding) >> 16;
temp2 = ip[3] + ((ip[3] * cospi8sqrt2minus1 + rounding) >> 16);
c1 = temp1 - temp2;
temp1 = ip[1] + ((ip[1] * cospi8sqrt2minus1 + rounding) >> 16);
temp2 = (ip[3] * sinpi8sqrt2 + rounding) >> 16;
d1 = temp1 + temp2;
op[0] = (a1 + d1 + 4) >> 3;
op[3] = (a1 - d1 + 4) >> 3;
op[1] = (b1 + c1 + 4) >> 3;
op[2] = (b1 - c1 + 4) >> 3;
ip += shortpitch;
op += shortpitch;
}
}
void vp8_short_idct4x4llm_1_c(short *input, short *output, int pitch)
{
int i;
int a1;
short *op = output;
int shortpitch = pitch >> 1;
a1 = ((input[0] + 4) >> 3);
for (i = 0; i < 4; i++)
{
op[0] = a1;
op[1] = a1;
op[2] = a1;
op[3] = a1;
op += shortpitch;
}
}
void vp8_dc_only_idct_c(short input_dc, short *output, int pitch)
{
int i;
int a1;
short *op = output;
int shortpitch = pitch >> 1;
a1 = ((input_dc + 4) >> 3);
for (i = 0; i < 4; i++)
{
op[0] = a1;
op[1] = a1;
op[2] = a1;
op[3] = a1;
op += shortpitch;
}
}
void vp8_short_inv_walsh4x4_c(short *input, short *output)
{
int i;
int a1, b1, c1, d1;
int a2, b2, c2, d2;
short *ip = input;
short *op = output;
for (i = 0; i < 4; i++)
{
a1 = ip[0] + ip[12];
b1 = ip[4] + ip[8];
c1 = ip[4] - ip[8];
d1 = ip[0] - ip[12];
op[0] = a1 + b1;
op[4] = c1 + d1;
op[8] = a1 - b1;
op[12] = d1 - c1;
ip++;
op++;
}
ip = output;
op = output;
for (i = 0; i < 4; i++)
{
a1 = ip[0] + ip[3];
b1 = ip[1] + ip[2];
c1 = ip[1] - ip[2];
d1 = ip[0] - ip[3];
a2 = a1 + b1;
b2 = c1 + d1;
c2 = a1 - b1;
d2 = d1 - c1;
op[0] = (a2 + 3) >> 3;
op[1] = (b2 + 3) >> 3;
op[2] = (c2 + 3) >> 3;
op[3] = (d2 + 3) >> 3;
ip += 4;
op += 4;
}
}
void vp8_short_inv_walsh4x4_1_c(short *input, short *output)
{
int i;
int a1;
short *op = output;
a1 = ((input[0] + 3) >> 3);
for (i = 0; i < 4; i++)
{
op[0] = a1;
op[1] = a1;
op[2] = a1;
op[3] = a1;
op += 4;
}
}
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