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/**
* FreeRDP: A Remote Desktop Protocol client.
* RemoteFX Codec Library - RLGR
*
* Copyright 2011 Vic Lee
* Copyright 2016-2017 Jay Sorg <jay.sorg@gmail.com>
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
/**
* This implementation of RLGR refers to
* [MS-RDPRFX] 3.1.8.1.7.3 RLGR1/RLGR3 Pseudocode
*/
#if defined(HAVE_CONFIG_H)
#include <config_ac.h>
#endif
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "rfxcommon.h"
#define PIXELS_IN_TILE 4096
/* Constants used within the RLGR1/RLGR3 algorithm */
#define KPMAX (80) /* max value for kp or krp */
#define LSGR (3) /* shift count to convert kp to k */
#define UP_GR (4) /* increase in kp after a zero run in RL mode */
#define DN_GR (6) /* decrease in kp after a nonzero symbol in RL mode */
#define UQ_GR (3) /* increase in kp after nonzero symbol in GR mode */
#define DQ_GR (3) /* decrease in kp after zero symbol in GR mode */
#define GetNextInput do { \
input = *coef; \
coef++; \
coef_size--; \
} while (0)
#define CheckWrite do { \
while (bit_count >= 8) \
{ \
bit_count -= 8; \
*cdata = bits >> bit_count; \
cdata++; \
} \
} while (0)
/* output GR code for (mag - 1) */
#define CodeGR(_krp, _lmag) do { \
int lkr = _krp >> LSGR; \
/* unary part of GR code */ \
int lvk = _lmag >> lkr; \
int llvk = lvk; \
while (llvk >= 8) \
{ \
bits <<= 8; \
bits |= 0xFF; \
llvk -= 8; \
*cdata = bits >> bit_count; \
cdata++; \
} \
bits <<= llvk; \
bits |= (1 << llvk) - 1; \
bit_count += llvk; \
bits <<= 1; \
bit_count++; \
CheckWrite; \
/* remainder part of GR code, if needed */ \
if (lkr) \
{ \
bits <<= lkr; \
bits |= _lmag & ((1 << lkr) - 1); \
bit_count += lkr; \
} \
/* update _krp, only if it is not equal to 1 */ \
if (lvk == 0) \
{ \
_krp = MAX(0, _krp - 2); \
} \
else if (lvk > 1) \
{ \
_krp = MIN(KPMAX, _krp + lvk); \
} \
} while (0)
int
rfx_encode_diff_rlgr1(sint16 *coef, uint8 *cdata, int cdata_size)
{
int k;
int kp;
int krp;
int input;
int numZeros;
int runmax;
int mag;
int sign;
int processed_size;
int lmag;
int coef_size;
int y;
int bit_count;
unsigned int bits;
uint8 *cdata_org;
uint32 twoMs;
/* the last 64 bytes are diff */
for (k = PIXELS_IN_TILE - 1; k > PIXELS_IN_TILE - 64; k--)
{
coef[k] -= coef[k - 1];
}
/* initialize the parameters */
k = 1;
kp = 1 << LSGR;
krp = 1 << LSGR;
bit_count = 0;
bits = 0;
cdata_org = cdata;
/* process all the input coefficients */
coef_size = PIXELS_IN_TILE;
while (coef_size > 0)
{
if (k)
{
/* RUN-LENGTH MODE */
/* collect the run of zeros in the input stream */
numZeros = 0;
GetNextInput;
while (input == 0 && coef_size > 0)
{
numZeros++;
GetNextInput;
}
/* emit output zeros */
runmax = 1 << k;
while (numZeros >= runmax)
{
bits <<= 1;
bit_count++;
CheckWrite;
numZeros -= runmax;
kp = MIN(KPMAX, kp + UP_GR);
k = kp >> LSGR;
runmax = 1 << k;
}
/* output a 1 to terminate runs */
bits <<= 1;
bits |= 1;
bit_count++;
/* output the remaining run length using k bits */
bits <<= k;
bits |= numZeros;
bit_count += k;
CheckWrite;
/* encode the nonzero value using GR coding */
if (input < 0)
{
mag = -input;
sign = 1;
}
else
{
mag = input;
sign = 0;
}
bits <<= 1;
bits |= sign;
bit_count++;
lmag = mag ? mag - 1 : 0;
CodeGR(krp, lmag); /* output GR code for (mag - 1) */
CheckWrite;
kp = MAX(0, kp - DN_GR);
k = kp >> LSGR;
}
else
{
/* GOLOMB-RICE MODE */
/* RLGR1 variant */
/* convert input to (2*magnitude - sign), encode using GR code */
GetNextInput;
y = input >> 15;
twoMs = (((input ^ y) - y) << 1) + y;
CodeGR(krp, twoMs);
CheckWrite;
/* update k, kp */
if (twoMs)
{
kp = MAX(0, kp - DQ_GR);
k = kp >> LSGR;
}
else
{
kp = MIN(KPMAX, kp + UQ_GR);
k = kp >> LSGR;
}
}
}
if (bit_count > 0)
{
bits <<= 8 - bit_count;
*cdata = bits;
cdata++;
bit_count = 0;
}
processed_size = cdata - cdata_org;
return processed_size;
}
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