--- /dev/null
+//
+// MMX32 iDCT algorithm (IEEE-1180 compliant) :: idct_mmx32()
+//
+// MPEG2AVI
+// --------
+// v0.16B33 initial release
+//
+// This was one of the harder pieces of work to code.
+// Intel's app-note focuses on the numerical issues of the algorithm, but
+// assumes the programmer is familiar with IDCT mathematics, leaving the
+// form of the complete function up to the programmer's imagination.
+
+#include "config.h"
+#include "mpeg2enc.h"
+#include "global.h"
+#include "simd.h"
+
+// ALGORITHM OVERVIEW
+// ------------------
+// I played around with the code for quite a few hours. I came up
+// with *A* working IDCT algorithm, however I'm not sure whether my routine
+// is "the correct one." But rest assured, my code passes all six IEEE
+// accuracy tests with plenty of 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) intermediate matrix transpose (mandatory)
+//
+// 3) IDCT-row transformation (2nd time) on all 8 rows of the intermediate
+// matrix. The output is 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 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 had to change some constants/variables for my method to work :
+//
+// As given by Intel, the #defines for SHIFT_INV_COL and RND_INV_COL are
+// wrong. Not surprising since I'm not using a true column-transform
+// operation, but the row-transform operation (as mentioned earlier.)
+// round_inv_col[], which is given as "4 int16_t" values, should have the
+// same dimensions as round_inv_row[]. The corrected variables are
+// shown.
+//
+// Intel's code defines a different table for each each row operation.
+// The tables given are 0/4, 1/7, 2/6, and 5/3. My code only uses row#0.
+// Using the other rows messes up the overall transform.
+//
+// IMPLEMENTATION DETAILs
+// ----------------------
+//
+// I divided the algorithm's work 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)
+//
+// The 2nd function is a clone of the 1st, with changes made only to the
+// shift&rounding instructions.
+//
+// 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.
+//
+// liaor@umcc.ais.org http://members.tripod.com/~liaor
+//
+
+//;=============================================================================
+//;
+//; 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)
+//;
+//;=============================================================================
+
+#define BITS_INV_ACC 4 //; 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 +14 ) // changed from Intel's val)
+
+
+#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) //; correction -1.0 and round
+
+/* TODO: This should *really* be aligned on 16-byte boundaries... */
+
+const int idct_r_inv_row[2] = { RND_INV_ROW, RND_INV_ROW};
+const int idct_r_inv_col[2] = {RND_INV_COL, RND_INV_COL};
+const int idct_r_inv_corr[2] = {RND_INV_CORR, RND_INV_CORR };
+
+/* Unused and thus redundant...
+const long long dct_one_corr = 0x0001000100010001;
+*/
+
+/*
+;=============================================================================
+;
+; The first stage iDCT 8x8 - inverse DCTs of rows
+;
+;-----------------------------------------------------------------------------
+; The 8-point inverse DCT direct algorithm
+;-----------------------------------------------------------------------------
+;
+; static const int16_t w[32] = {
+; FIX(cos_4_16), FIX(cos_2_16), FIX(cos_4_16), FIX(cos_6_16),
+; FIX(cos_4_16), FIX(cos_6_16), -FIX(cos_4_16), -FIX(cos_2_16),
+; FIX(cos_4_16), -FIX(cos_6_16), -FIX(cos_4_16), FIX(cos_2_16),
+; FIX(cos_4_16), -FIX(cos_2_16), FIX(cos_4_16), -FIX(cos_6_16),
+; FIX(cos_1_16), FIX(cos_3_16), FIX(cos_5_16), FIX(cos_7_16),
+; FIX(cos_3_16), -FIX(cos_7_16), -FIX(cos_1_16), -FIX(cos_5_16),
+; FIX(cos_5_16), -FIX(cos_1_16), FIX(cos_7_16), FIX(cos_3_16),
+; FIX(cos_7_16), -FIX(cos_5_16), FIX(cos_3_16), -FIX(cos_1_16) };
+;
+; #define DCT_8_INV_ROW(x, y)
+
+;{
+; int a0, a1, a2, a3, b0, b1, b2, b3;
+;
+; a0 =x[0]*w[0]+x[2]*w[1]+x[4]*w[2]+x[6]*w[3];
+; a1 =x[0]*w[4]+x[2]*w[5]+x[4]*w[6]+x[6]*w[7];
+; a2 = x[0] * w[ 8] + x[2] * w[ 9] + x[4] * w[10] + x[6] * w[11];
+; a3 = x[0] * w[12] + x[2] * w[13] + x[4] * w[14] + x[6] * w[15];
+; b0 = x[1] * w[16] + x[3] * w[17] + x[5] * w[18] + x[7] * w[19];
+; b1 = x[1] * w[20] + x[3] * w[21] + x[5] * w[22] + x[7] * w[23];
+; b2 = x[1] * w[24] + x[3] * w[25] + x[5] * w[26] + x[7] * w[27];
+; b3 = x[1] * w[28] + x[3] * w[29] + x[5] * w[30] + x[7] * w[31];
+;
+; y[0] = SHIFT_ROUND ( a0 + b0 );
+; y[1] = SHIFT_ROUND ( a1 + b1 );
+; y[2] = SHIFT_ROUND ( a2 + b2 );
+; y[3] = SHIFT_ROUND ( a3 + b3 );
+; y[4] = SHIFT_ROUND ( a3 - b3 );
+; y[5] = SHIFT_ROUND ( a2 - b2 );
+; y[6] = SHIFT_ROUND ( a1 - b1 );
+; y[7] = SHIFT_ROUND ( a0 - b0 );
+;}
+;
+;-----------------------------------------------------------------------------
+;
+; In this implementation the outputs of the iDCT-1D are multiplied
+; for rows 0,4 - by cos_4_16,
+; for rows 1,7 - by cos_1_16,
+; for rows 2,6 - by cos_2_16,
+; for rows 3,5 - by cos_3_16
+; and are shifted to the left for better accuracy
+;
+; For the constants used,
+; FIX(float_const) = (int16_t) (float_const * (1<<15) + 0.5)
+;
+;=============================================================================
+*/
+
+/* CONCATENATED TABLE, rows 0,1,2,3,4,5,6,7 (in order )
+
+ In our implementation, however, we only use row0 !
+*/
+
+const int16_t idct_tab_01234567[] = {
+ //row0, this row is required
+ 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
+
+ // the rest of these rows (1-7), aren't used !
+
+ //row1
+ 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
+
+ //row2
+ 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
+
+ //row3
+ 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
+
+ //row4
+ 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
+
+ //row5
+ 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
+
+ //row6
+ 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
+
+ //row7
+ 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
projects / goodguy / history.git / blobdiff