idctmmx.cpp

mpeg2编码解码源程序代码

#include "config.h"

//////////////////////////////////////////////////////////////////////
//  not functional
//////////////////////////////////////////////////////////////////////
// MPEG2AVI
// -------- 
//  v0.16B34
//    performance optimization, idct_mmx32_rows() and idct_mmx32_cols() now
//    transpose their respective outputs "in-place" (saves a bit of time)
//
//  v0.16B33 initial release
//
// MMX32 iDCT algorithm  (IEEE-1180 compliant) :: idct_mmx32()
//
//  This IDCT implementation is based on Intel Application Note AP-922.
//
//  This file implements the idct algorithm with no transpose.
//  The other file (idctmm32_transpose.c) is faster, but transposes the 
//  output-matrix.  (Intel's code-listing produces a transposed output.)
//
//  ALGORITHM OVERVIEW
//  ------------------
// This was one of the harder pieces of work to code.
// Intel's app-note focuses on the numerical theory/issues of the IDCT 
// implementation, but assumes the programmer is familiar with the
// requisite mathematics, leaving the exact form of the complete IDCT 
// code-listing up to the programmer's imagination.
//
// I played around with Intel's code-fragments for quite a few hours.  
// This file is *A* working IDCT implementation, but it may not be
// the implementation Intel originally intended.  Rest assured, I've
// done everything in my power to guarantee its correctness. 
// This implementation passes all six IEEE accuracy tests by a fair margin.
//
//   My IDCT algorithm consists of 4 steps:
//
//   1) IDCT-row transformation (using the IDCT-row function) on all 8 rows
//      This yields an intermediate 8x8 matrix.
//
//   2) transpose of intermediate matrix (mandatory)
//
//   3) IDCT-row transformation (2nd time) on all 8 rows of the 
//      intermediate matrix.
//      At this point, we have the final-result, in transposed form.
//
//   4) post-transformation matrix transpose 
//      (not necessary if the input-data is already transposed, this could
//       be done during the MPEG "zig-zag" scan, but since my algorithm
//       requires at least one transpose operation, why not re-use the
//       transpose-code.)
//
//   Although the (1st) and (3rd) steps use the same basic row-transform 
//   operation, the (3rd) step uses different shift&round constants 
//   (explained later.)
//
//   Also note that the intermediate transpose (2) would not be neccessary,
//   if the subsequent operation were a iDCT-column transformation.  Since
//   we only have the iDCT-row transform, we transpose the intermediate
//   matrix and use the iDCT-row transform a 2nd time.  I suppose one
//   a faster (but more complicated) code-implementation is possible, 
//   if these steps were merged.
//
//   I had to change some constants/variables for my method to work :
//
//      As given by Intel, #SHIFT_INV_COL and #RND_INV_COL are wrong.  
//      Not surprising since I'm probably implementing the IDCT in
//      perverse fashion.  
//      round_inv_col[], which is given as "4 short" values, should have the
//      same dimensions as round_inv_row[].  The corrected variables are 
//      shown.
//
//      Intel's code defines 4 tables of constants.  My code only uses only
//      one of these tables, row#0.  
//
//   IMPLEMENTATION DETAILs
//   ----------------------
// 
//   I divided the 4-steps of my algorithm into two subroutines,
//    1) idct_mmx32_rows() - transforms 8 rows, then transpose
//    2) idct_mmx32_cols() - transforms 8 rows, then transpose
//       yields final result ("drop-in" direct replacement for INT32 IDCT)
//
//   idct_mmx32_cols() is a carbon-copy of idct_mmx32_rows(), i.e. both
//   execute a row-by-row transformations.  Only the shift&rounding 
//   coefficients differ.
//
//      In the 1st function (rows), the shift & round instructions use 
//       SHIFT_INV_ROW & round_inv_row[] (renamed to r_inv_row[])
//
//      In the 2nd function (cols)-> r_inv_col[], and
//       SHIFT_INV_COL & round_inv_col[] (renamed to r_inv_col[])
//
//   Each function contains an integrated transpose-operator, which comes
//   AFTER the primary transformation operation.  In the future, I'll optimize
//   the code to do more of the transpose-work "in-place".  Right now, I've
//   left the code as two subroutines and a main calling function, so other
//   people can read the code more easily.


//;=============================================================================
//;
//;  AP-922   http://developer.intel.com/vtune/cbts/strmsimd
//; These examples contain code fragments for first stage iDCT 8x8
//; (for rows) and first stage DCT 8x8 (for columns)
//;
//;=============================================================================
#include "global.h"


#define BITS_INV_ACC	5	// 4 or 5 for IEEE
// 5 yields higher accuracy, but lessens dynamic range on the input matrix
#define SHIFT_INV_ROW	(16 - BITS_INV_ACC)
#define SHIFT_INV_COL	(1 + BITS_INV_ACC )
#define RND_INV_ROW		(1 << (SHIFT_INV_ROW-1))
#define RND_INV_COL		(1 << (SHIFT_INV_COL-1)) 
#define RND_INV_CORR	(RND_INV_COL - 1)

const static int r_inv_row[2] = { RND_INV_ROW, RND_INV_ROW};
const static int r_inv_col[2] = {RND_INV_COL, RND_INV_COL};
const static int r_inv_corr[2] = {RND_INV_CORR, RND_INV_CORR};

#define mword  qword
#define mptr mword ptr


#define BITS_FRW_ACC  3 			// 2 or 3 for accuracy
#define SHIFT_FRW_COL BITS_FRW_ACC
#define SHIFT_FRW_ROW  BITS_FRW_ACC + 17
#define RND_FRW_ROW  262144 * (BITS_FRW_ACC - 1)	// 1 << (SHIFT_FRW_ROW-1)

static short tab_i_01234567[] = {
	16384, 16384, 16384, -16384, 21407, 8867, 8867, -21407,
	16384, -16384, 16384, 16384, -8867, 21407, -21407, -8867,
	22725, 12873, 19266, -22725, 19266, 4520, -4520, -12873,
	12873, 4520, 4520, 19266, -22725, 19266, -12873, -22725,
};
static short tab_i_04[] = { 16384,  16384,  16384, -16384,  //	 movq-> w06 w04 w02 w00
		21407,   8867,   8867, -21407,	// w07 w05 w03 w01
		16384, -16384,  16384,  16384,	// w14 w12 w10 w08
		-8867,  21407, -21407,  -8867,	// w15 w13 w11 w09
		22725,  12873,  19266, -22725,	// w22 w20 w18 w16
		19266,   4520,  -4520, -12873,	// w23 w21 w19 w17
		12873,   4520,   4520,  19266,	// w30 w28 w26 w24
		-22725,  19266, -12873, -22725,	// w31 w29 w27 w25
};
static short tab_i_17[] = { 22725,  22725,  22725, -22725,	// movq-> w06 w04 w02 w00
		29692,  12299,  12299, -29692,	// w07 w05 w03 w01
		22725, -22725,  22725,  22725,	// w14 w12 w10 w08
		-12299,  29692, -29692, -12299,	// w15 w13 w11 w09
		31521,  17855,  26722, -31521,	// w22 w20 w18 w16
		26722,   6270,  -6270, -17855,	// w23 w21 w19 w17
		17855,   6270,   6270,  26722,	// w30 w28 w26 w24
		-31521,  26722, -17855, -31521,	// w31 w29 w27 w25
};
static short tab_i_26	[] = { 21407,  21407,  21407, -21407,	// movq-> w06 w04 w02 w00
		  27969,  11585,  11585, -27969	,// w07 w05 w03 w01
		  21407, -21407,  21407,  21407,	// w14 w12 w10 w08
		 -11585,  27969, -27969, -11585,	// w15 w13 w11 w09
		  29692,  16819,  25172, -29692,	// w22 w20 w18 w16
		  25172,   5906,  -5906, -16819,	// w23 w21 w19 w17
		  16819,   5906,   5906,  25172,	// w30 w28 w26 w24
		 -29692,  25172, -16819, -29692,	// w31 w29 w27 w25
};
static short tab_i_35	[] = { 19266,  19266,  19266, -19266,	// movq-> w06 w04 w02 w00
		  25172,  10426,  10426, -25172,	// w07 w05 w03 w01
		  19266, -19266,  19266,  19266,	// w14 w12 w10 w08
		 -10426,  25172, -25172, -10426,// w15 w13 w11 w09
		  26722,  15137,  22654, -26722,// w22 w20 w18 w16
		  22654,   5315,  -5315, -15137,	// w23 w21 w19 w17
		  15137,   5315,   5315,  22654,	// w30 w28 w26 w24
		 -26722,  22654, -15137, -26722,// w31 w29 w27 w25
};
static const short one_corr[] ={1,            1,            1,            1};
static const unsigned int round_inv_row	[] = {  RND_INV_ROW,  RND_INV_ROW };
static const short round_inv_col[] = { RND_INV_COL,  RND_INV_COL,  RND_INV_COL, RND_INV_COL};
static const short round_inv_corr[] = { RND_INV_CORR, RND_INV_CORR, RND_INV_CORR, RND_INV_CORR};
static const unsigned int round_frw_row[] = { RND_FRW_ROW,  RND_FRW_ROW};

static const short tg_1_16[] = {13036,  13036,  13036,  13036};		// tg * (2<<16) + 0.5
static const short tg_2_16[] = {27146,  27146,  27146,  27146} 	;	//tg * (2<<16) + 0.5
static const short tg_3_16[] = {-21746, -21746, -21746, -21746} 	;	//tg * (2<<16) + 0.5
static const short cos_4_16[] = {-19195, -19195, -19195, -19195} 	;	//cos * (2<<16) + 0.5
static const short ocos_4_16[] = {23170,  23170,  23170,  23170}	;	//cos * (2<<15) + 0.5
static const short otg_3_16[] = { 21895, 21895, 21895, 21895 }	;	//tg * (2<<16) + 0.5

//; assume SHIFT_INV_ROW == 11
static unsigned int rounder_0[] ={ 65536, 65536};
static unsigned int rounder_4[] ={  0,     0};
static unsigned int rounder_1[] ={  3597,  3597};
static unsigned int rounder_7[] ={ 512,   512};
static unsigned int rounder_2[] ={ 2260,  2260};
static unsigned int rounder_6[] ={  512,   512};
static unsigned int rounder_3[] ={ 1203,  1203};
static unsigned int rounder_5[] ={   120,   120};