/* * fdct BlackFin * * Copyright (C) 2007 Marc Hoffman <marc.hoffman@analog.com> * * This file is part of FFmpeg. * * FFmpeg is free software; you can redistribute it and/or * modify it under the terms of the GNU Lesser General Public * License as published by the Free Software Foundation; either * version 2.1 of the License, or (at your option) any later version. * * FFmpeg is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU * Lesser General Public License for more details. * * You should have received a copy of the GNU Lesser General Public * License along with FFmpeg; if not, write to the Free Software * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA */ /* void ff_bfin_fdct (DCTELEM *buf); This implementation works only for 8x8 input. The range of input must be -256 to 255 i.e. 8bit input represented in a 16bit data word. The original data must be sign extended into the 16bit data words. Chen factorization of 8 X(m) = sum (x(n) * cos ((2n+1)*m*pi/16)) n=0 C4 0 --*-------------*0+7---*-----*0+3-------*-*-------------------> 0 \ / \ / X S4,S4 1 --*-\---------/-*1+6---*-\-/-*1+2-------*-*-------------------> 4 \ / \ -C4 C3 2 --*---\-----/---*2+5---*-/-\-*1-2---------------*-*-----------> 2 \ / / \ X S3,-S3 3 --*-----\-/-----*3+4---*-----*0-3---------------*-*-----------> 6 / C7 C3 4 --*-----/-\-----*3-4------------*-*4+5--*-----*---------------> 1 / \ -C4 X \ /S7 C3 5 --*---/-----\---*2-5---*-*------*=*4-5----\-/------*-*--------> 5 / \ X S4,S4 / X S3,-S3 6 --*-/---------\-*1-6---*-*------*=*7-6----/-\------*-*--------> 3 / \ C4 X / \-S7 C3 --*-------------*0-7------------*-*7+6--*-----*---------------> 7 C7 Notation Cn = cos(n*pi/8) used throughout the code. Registers used: R0, R1, R2, R3, R4, R5, R6,R7, P0, P1, P2, P3, P4, P5, A0, A1. Other registers used: I0, I1, I2, I3, B0, B2, B3, M0, M1, L3 registers and LC0. Input - r0 - pointer to start of DCTELEM *block Output - The DCT output coefficients in the DCTELEM *block Register constraint: This code is called from jpeg_encode. R6, R5, R4 if modified should be stored and restored. Performance: (Timer version 0.6.33) Code Size : 240 Bytes. Memory Required : Input Matrix : 8 * 8 * 2 Bytes. Coefficients : 16 Bytes Temporary matrix: 8 * 8 * 2 Bytes. Cycle Count :26+{18+8*(14+2S)}*2 where S -> Stalls (7.45 c/pel) ----------------------------------------- | Size | Forward DCT | Inverse DCT | ----------------------------------------- | 8x8 | 284 Cycles | 311 Cycles | ----------------------------------------- Ck = int16(cos(k/16*pi)*32767+.5)/2 #define C4 23170 #define C3 13623 #define C6 6270 #define C7 3196 Sk = int16(sin(k/16*pi)*32767+.5)/2 #define S4 11585 #define S3 9102 #define S6 15137 #define S7 16069 the coefficients are ordered as follows: short dct_coef[] C4,S4, C6,S6, C7,S7, S3,C3, ----------------------------------------------------------- FFMPEG conformance testing results ----------------------------------------------------------- dct-test: modified with the following dct_error("BFINfdct", 0, ff_bfin_fdct, fdct, test); produces the following output: root:/u/ffmpeg/bhead/libavcodec> ./dct-test ffmpeg DCT/IDCT test 2 -131 -6 -48 -36 33 -83 24 34 52 -24 -15 5 92 57 143 -67 -43 -1 74 -16 5 -71 32 -78 106 92 -34 -38 81 20 -18 7 -62 40 2 -15 90 -62 -83 -83 1 -104 -13 43 -19 7 11 -63 31 12 -29 83 72 21 10 -17 -63 -15 73 50 -91 159 -14 DCT BFINfdct: err_inf=2 err2=0.16425938 syserr=0.00795000 maxout=2098 blockSumErr=27 DCT BFINfdct: 92.1 kdct/s root:/u/ffmpeg/bhead/libavcodec> */ #include "config_bfin.h" .section .l1.data.B,"aw",@progbits .align 4; dct_coeff: .short 0x5a82, 0x2d41, 0x187e, 0x3b21, 0x0c7c, 0x3ec5, 0x238e, 0x3537; .section .l1.data.A,"aw",@progbits .align 4 vtmp: .space 128 DEFUN(fdct,mL1, (DCTELEM *block)): [--SP] = (R7:4, P5:3); // Push the registers onto the stack. b0 = r0; r0 = [P3+dct_coeff@GOT17M4]; b3 = r0; r0 = [P3+vtmp@GOT17M4]; b2 = r0; L3 = 16; // L3 is set to 16 to make the coefficient // array Circular. //---------------------------------------------------------------------------- /* * I0, I1, and I2 registers are used to read the input data. I3 register is used * to read the coefficients. P0 and P1 registers are used for writing the output * data. */ M0 = 12 (X); // All these initializations are used in the M1 = 16 (X); // modification of address offsets. M2 = 128 (X); P2 = 16; P3 = 32 (X); P4 = -110 (X); P5 = -62 (X); P0 = 2(X); // Prescale the input to get the correct precision. i0=b0; i1=b0; lsetup (.0, .1) LC0 = P3; r0=[i0++]; .0: r1=r0<<3 (v) || r0=[i0++] ; .1: [i1++]=r1; /* * B0 points to the "in" buffer. * B2 points to "temp" buffer in the first iteration. */ lsetup (.2, .3) LC0 = P0; .2: I0 = B0; // I0 points to Input Element (0, 0). I1 = B0; // Element 1 and 0 is read in R0. I1 += M0 || R0 = [I0++]; // I1 points to Input Element (0, 6). I2 = I1; // Element 6 is read into R3.H. I2 -= 4 || R3.H = W[I1++]; // I2 points to Input Element (0, 4). I3 = B3; // I3 points to Coefficients. P0 = B2; // P0 points to temporary array Element // (0, 0). P1 = B2; // P1 points to temporary array. R7 = [P1++P2] || R2 = [I2++]; // P1 points to temporary array // Element (1, 0). // R7 is a dummy read. X4,X5 // are read into R2. R3.L = W[I1--]; // X7 is read into R3.L. R1.H = W[I0++]; // X2 is read into R1.H. /* * X0 = (X0 + X7) / 2. * X1 = (X1 + X6) / 2. * X6 = (X1 - X6) / 2. * X7 = (X0 - X7) / 2. * It reads the data 3 in R1.L. */ R0 = R0 +|+ R3, R3 = R0 -|- R3 || R1.L = W[I0++] || NOP; /* * X2 = (X2 + X5) / 2. * X3 = (X3 + X4) / 2. * X4 = (X3 - X4) / 2. * X5 = (X2 - X5) / 2. * R7 = C4 = cos(4*pi/16) */ R1 = R1 +|+ R2, R2 = R1 -|- R2 (CO) || NOP || R7 = [I3++]; /* * At the end of stage 1 R0 has (1,0), R1 has (2,3), R2 has (4, 5) and * R3 has (6,7). * Where the notation (x, y) represents uper/lower half pairs. */ /* * X0 = X0 + X3. * X1 = X1 + X2. * X2 = X1 - X2. * X3 = X0 - X3. */ R0 = R0 +|+ R1, R1 = R0 -|- R1; lsetup (.row0, .row1) LC1 = P2 >> 1; // 1d dct, loops 8x .row0: /* * This is part 2 computation continued..... * A1 = X6 * cos(pi/4) * A0 = X6 * cos(pi/4) * A1 = A1 - X5 * cos(pi/4) * A0 = A0 + X5 * cos(pi/4). * The instruction W[I0] = R3.L is used for packing it to R2.L. */ A1=R3.H*R7.l, A0=R3.H*R7.l || I1+=M1 || W[I0] = R3.L; R4.H=(A1-=R2.L*R7.l), R4.L=(A0+=R2.L*R7.l) || I2+=M0 || NOP; /* R0 = (X1,X0) R1 = (X2,X3) R4 = (X5, X6). */ /* * A1 = X0 * cos(pi/4) * A0 = X0 * cos(pi/4) * A1 = A1 - X1 * cos(pi/4) * A0 = A0 + X1 * cos(pi/4) * R7 = (C2,C6) */ A1=R0.L*R7.h, A0=R0.L*R7.h || NOP || R3.H=W[I1++]; R5.H=(A1-=R0.H*R7.h),R5.L=(A0+=R0.H*R7.h) || R7=[I3++] || NOP; /* * A1 = X2 * cos(3pi/8) * A0 = X3 * cos(3pi/8) * A1 = A1 + X3 * cos(pi/8) * A0 = A0 - X2 * cos(pi/8) * R3 = cos(pi/4) * R7 = (cos(7pi/8),cos(pi/8)) * X4 = X4 + X5. * X5 = X4 - X5. * X6 = X7 - X6. * X7 = X7 + X6. */ A1=R1.H*R7.L, A0=R1.L*R7.L || W[P0++P3]=R5.L || R2.L=W[I0]; R2=R2+|+R4, R4=R2-|-R4 || I0+=4 || R3.L=W[I1--]; R6.H=(A1+=R1.L*R7.H),R6.L=(A0 -= R1.H * R7.H) || I0+=4 || R7=[I3++]; /* R2 = (X4, X7) R4 = (X5,X6) R5 = (X1, X0) R6 = (X2,X3). */ /* * A1 = X4 * cos(7pi/16) * A0 = X7 * cos(7pi/16) * A1 = A1 + X7 * cos(pi/16) * A0 = A0 - X4 * cos(pi/16) */ A1=R2.H*R7.L, A0=R2.L*R7.L || W[P0++P3]=R6.H || R0=[I0++]; R2.H=(A1+=R2.L*R7.H),R2.L=(A0-=R2.H*R7.H) || W[P0++P3]=R5.H || R7=[I3++]; /* * A1 = X5 * cos(3pi/16) * A0 = X6 * cos(3pi/16) * A1 = A1 + X6 * cos(5pi/16) * A0 = A0 - X5 * cos(5pi/16) * The output values are written. */ A1=R4.H*R7.H, A0=R4.L*R7.H || W[P0++P2]=R6.L || R1.H=W[I0++]; R4.H=(A1+=R4.L*R7.L),R4.L=(A0-=R4.H*R7.L) || W[P0++P4]=R2.L || R1.L=W[I0++]; /* Beginning of next stage, **pipelined** + drain and store the rest of the column store. */ R0=R0+|+R3,R3=R0-|-R3 || W[P1++P3]=R2.H || R2=[I2++]; R1=R1+|+R2,R2=R1-|-R2 (CO) || W[P1++P3]=R4.L || R7=[I3++]; .row1: R0=R0+|+R1,R1=R0-|-R1 || W[P1++P5]=R4.H || NOP; // Exchange input with output. B1 = B0; B0 = B2; .3: B2 = B1; L3=0; (r7:4,p5:3) = [sp++]; RTS;