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ffmpeg/libavcodec/armv4l/simple_idct_arm.S
Diego Biurrun f7b106cb35 Switch license from GPL to LGPL. The original author agreed to this as 
stated in the commit message adding this file.

Originally committed as revision 6181 to svn://svn.ffmpeg.org/ffmpeg/trunk
2006-09-06 10:17:28 +00:00

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22 KiB
ArmAsm
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/*
* simple_idct_arm.S
* Copyright (C) 2002 Frederic 'dilb' Boulay.
* All Rights Reserved.
*
* Author: Frederic Boulay <dilb@handhelds.org>
*
* This library 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 of the License, or (at your option) any later version.
*
* This library 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 this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* The function defined in this file, is derived from the simple_idct function
* from the libavcodec library part of the ffmpeg project.
*/
/* useful constants for the algorithm, they are save in __constant_ptr__ at */
/* the end of the source code.*/
#define W1 22725
#define W2 21407
#define W3 19266
#define W4 16383
#define W5 12873
#define W6 8867
#define W7 4520
#define MASK_MSHW 0xFFFF0000
/* offsets of the constants in the vector */
#define offW1 0
#define offW2 4
#define offW3 8
#define offW4 12
#define offW5 16
#define offW6 20
#define offW7 24
#define offMASK_MSHW 28
#define ROW_SHIFT 11
#define ROW_SHIFT2MSHW (16-11)
#define COL_SHIFT 20
#define ROW_SHIFTED_1 1024 /* 1<< (ROW_SHIFT-1) */
#define COL_SHIFTED_1 524288 /* 1<< (COL_SHIFT-1) */
.text
.align
.global simple_idct_ARM
simple_idct_ARM:
@@ void simple_idct_ARM(int16_t *block)
@@ save stack for reg needed (take all of them),
@@ R0-R3 are scratch regs, so no need to save them, but R0 contains the pointer to block
@@ so it must not be overwritten, if it is not saved!!
@@ R12 is another scratch register, so it should not be saved too
@@ save all registers
stmfd sp!, {r4-r11, r14} @ R14 is also called LR
@@ at this point, R0=block, other registers are free.
add r14, r0, #112 @ R14=&block[8*7], better start from the last row, and decrease the value until row=0, i.e. R12=block.
add r12, pc, #(__constant_ptr__-.-8) @ R12=__constant_ptr__, the vector containing the constants, probably not necessary to reserve a register for it
@@ add 2 temporary variables in the stack: R0 and R14
sub sp, sp, #8 @ allow 2 local variables
str r0, [sp, #0] @ save block in sp[0]
@@ stack status
@@ sp+4 free
@@ sp+0 R0 (block)
@@ at this point, R0=block, R14=&block[56], R12=__const_ptr_, R1-R11 free
__row_loop:
@@ read the row and check if it is null, almost null, or not, according to strongarm specs, it is not necessary to optimise ldr accesses (i.e. split 32bits in 2 16bits words), at least it gives more usable registers :)
ldr r1, [r14, #0] @ R1=(int32)(R12)[0]=ROWr32[0] (relative row cast to a 32b pointer)
ldr r2, [r14, #4] @ R2=(int32)(R12)[1]=ROWr32[1]
ldr r3, [r14, #8] @ R3=ROWr32[2]
ldr r4, [r14, #12] @ R4=ROWr32[3]
@@ check if the words are null, if all of them are null, then proceed with next row (branch __end_row_loop),
@@ if ROWr16[0] is the only one not null, then proceed with this special case (branch __almost_empty_row)
@@ else follow the complete algorithm.
@@ at this point, R0=block, R14=&block[n], R12=__const_ptr_, R1=ROWr32[0], R2=ROWr32[1],
@@ R3=ROWr32[2], R4=ROWr32[3], R5-R11 free
orr r5, r4, r3 @ R5=R4 | R3
orr r5, r5, r2 @ R5=R4 | R3 | R2
orrs r6, r5, r1 @ Test R5 | R1 (the aim is to check if everything is null)
beq __end_row_loop
mov r7, r1, asr #16 @ R7=R1>>16=ROWr16[1] (evaluate it now, as it could be useful later)
ldrsh r6, [r14, #0] @ R6=ROWr16[0]
orrs r5, r5, r7 @ R5=R4 | R3 | R2 | R7
beq __almost_empty_row
__b_evaluation:
@@ at this point, R0=block (temp), R1(free), R2=ROWr32[1], R3=ROWr32[2], R4=ROWr32[3],
@@ R5=(temp), R6=ROWr16[0], R7=ROWr16[1], R8-R11 free,
@@ R12=__const_ptr_, R14=&block[n]
@@ to save some registers/calls, proceed with b0-b3 first, followed by a0-a3
@@ MUL16(b0, W1, row[1]);
@@ MUL16(b1, W3, row[1]);
@@ MUL16(b2, W5, row[1]);
@@ MUL16(b3, W7, row[1]);
@@ MAC16(b0, W3, row[3]);
@@ MAC16(b1, -W7, row[3]);
@@ MAC16(b2, -W1, row[3]);
@@ MAC16(b3, -W5, row[3]);
ldr r8, [r12, #offW1] @ R8=W1
mov r2, r2, asr #16 @ R2=ROWr16[3]
mul r0, r8, r7 @ R0=W1*ROWr16[1]=b0 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
ldr r9, [r12, #offW3] @ R9=W3
ldr r10, [r12, #offW5] @ R10=W5
mul r1, r9, r7 @ R1=W3*ROWr16[1]=b1 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
ldr r11, [r12, #offW7] @ R11=W7
mul r5, r10, r7 @ R5=W5*ROWr16[1]=b2 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
mul r7, r11, r7 @ R7=W7*ROWr16[1]=b3 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
teq r2, #0 @ if null avoid muls
mlane r0, r9, r2, r0 @ R0+=W3*ROWr16[3]=b0 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
rsbne r2, r2, #0 @ R2=-ROWr16[3]
mlane r1, r11, r2, r1 @ R1-=W7*ROWr16[3]=b1 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
mlane r5, r8, r2, r5 @ R5-=W1*ROWr16[3]=b2 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
mlane r7, r10, r2, r7 @ R7-=W5*ROWr16[3]=b3 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
@@ at this point, R0=b0, R1=b1, R2 (free), R3=ROWr32[2], R4=ROWr32[3],
@@ R5=b2, R6=ROWr16[0], R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
@@ R12=__const_ptr_, R14=&block[n]
@@ temp = ((uint32_t*)row)[2] | ((uint32_t*)row)[3];
@@ if (temp != 0) {}
orrs r2, r3, r4 @ R2=ROWr32[2] | ROWr32[3]
beq __end_b_evaluation
@@ at this point, R0=b0, R1=b1, R2 (free), R3=ROWr32[2], R4=ROWr32[3],
@@ R5=b2, R6=ROWr16[0], R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
@@ R12=__const_ptr_, R14=&block[n]
@@ MAC16(b0, W5, row[5]);
@@ MAC16(b2, W7, row[5]);
@@ MAC16(b3, W3, row[5]);
@@ MAC16(b1, -W1, row[5]);
@@ MAC16(b0, W7, row[7]);
@@ MAC16(b2, W3, row[7]);
@@ MAC16(b3, -W1, row[7]);
@@ MAC16(b1, -W5, row[7]);
mov r3, r3, asr #16 @ R3=ROWr16[5]
teq r3, #0 @ if null avoid muls
mlane r0, r10, r3, r0 @ R0+=W5*ROWr16[5]=b0
mov r4, r4, asr #16 @ R4=ROWr16[7]
mlane r5, r11, r3, r5 @ R5+=W7*ROWr16[5]=b2
mlane r7, r9, r3, r7 @ R7+=W3*ROWr16[5]=b3
rsbne r3, r3, #0 @ R3=-ROWr16[5]
mlane r1, r8, r3, r1 @ R7-=W1*ROWr16[5]=b1
@@ R3 is free now
teq r4, #0 @ if null avoid muls
mlane r0, r11, r4, r0 @ R0+=W7*ROWr16[7]=b0
mlane r5, r9, r4, r5 @ R5+=W3*ROWr16[7]=b2
rsbne r4, r4, #0 @ R4=-ROWr16[7]
mlane r7, r8, r4, r7 @ R7-=W1*ROWr16[7]=b3
mlane r1, r10, r4, r1 @ R1-=W5*ROWr16[7]=b1
@@ R4 is free now
__end_b_evaluation:
@@ at this point, R0=b0, R1=b1, R2=ROWr32[2] | ROWr32[3] (tmp), R3 (free), R4 (free),
@@ R5=b2, R6=ROWr16[0], R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
__a_evaluation:
@@ a0 = (W4 * row[0]) + (1 << (ROW_SHIFT - 1));
@@ a1 = a0 + W6 * row[2];
@@ a2 = a0 - W6 * row[2];
@@ a3 = a0 - W2 * row[2];
@@ a0 = a0 + W2 * row[2];
ldr r9, [r12, #offW4] @ R9=W4
mul r6, r9, r6 @ R6=W4*ROWr16[0]
ldr r10, [r12, #offW6] @ R10=W6
ldrsh r4, [r14, #4] @ R4=ROWr16[2] (a3 not defined yet)
add r6, r6, #ROW_SHIFTED_1 @ R6=W4*ROWr16[0] + 1<<(ROW_SHIFT-1) (a0)
mul r11, r10, r4 @ R11=W6*ROWr16[2]
ldr r8, [r12, #offW2] @ R8=W2
sub r3, r6, r11 @ R3=a0-W6*ROWr16[2] (a2)
@@ temp = ((uint32_t*)row)[2] | ((uint32_t*)row)[3];
@@ if (temp != 0) {}
teq r2, #0
beq __end_bef_a_evaluation
add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
mul r11, r8, r4 @ R11=W2*ROWr16[2]
sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
@@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
@@ R5=b2, R6=a0, R7=b3, R8=W2, R9=W4, R10=W6, R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
@@ a0 += W4*row[4]
@@ a1 -= W4*row[4]
@@ a2 -= W4*row[4]
@@ a3 += W4*row[4]
ldrsh r11, [r14, #8] @ R11=ROWr16[4]
teq r11, #0 @ if null avoid muls
mulne r11, r9, r11 @ R11=W4*ROWr16[4]
@@ R9 is free now
ldrsh r9, [r14, #12] @ R9=ROWr16[6]
addne r6, r6, r11 @ R6+=W4*ROWr16[4] (a0)
subne r2, r2, r11 @ R2-=W4*ROWr16[4] (a1)
subne r3, r3, r11 @ R3-=W4*ROWr16[4] (a2)
addne r4, r4, r11 @ R4+=W4*ROWr16[4] (a3)
@@ W6 alone is no more useful, save W2*ROWr16[6] in it instead
teq r9, #0 @ if null avoid muls
mulne r11, r10, r9 @ R11=W6*ROWr16[6]
addne r6, r6, r11 @ R6+=W6*ROWr16[6] (a0)
mulne r10, r8, r9 @ R10=W2*ROWr16[6]
@@ a0 += W6*row[6];
@@ a3 -= W6*row[6];
@@ a1 -= W2*row[6];
@@ a2 += W2*row[6];
subne r4, r4, r11 @ R4-=W6*ROWr16[6] (a3)
subne r2, r2, r10 @ R2-=W2*ROWr16[6] (a1)
addne r3, r3, r10 @ R3+=W2*ROWr16[6] (a2)
__end_a_evaluation:
@@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
@@ R5=b2, R6=a0, R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
@@ row[0] = (a0 + b0) >> ROW_SHIFT;
@@ row[1] = (a1 + b1) >> ROW_SHIFT;
@@ row[2] = (a2 + b2) >> ROW_SHIFT;
@@ row[3] = (a3 + b3) >> ROW_SHIFT;
@@ row[4] = (a3 - b3) >> ROW_SHIFT;
@@ row[5] = (a2 - b2) >> ROW_SHIFT;
@@ row[6] = (a1 - b1) >> ROW_SHIFT;
@@ row[7] = (a0 - b0) >> ROW_SHIFT;
add r8, r6, r0 @ R8=a0+b0
add r9, r2, r1 @ R9=a1+b1
@@ put 2 16 bits half-words in a 32bits word
@@ ROWr32[0]=ROWr16[0] | (ROWr16[1]<<16) (only Little Endian compliant then!!!)
ldr r10, [r12, #offMASK_MSHW] @ R10=0xFFFF0000
and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a1+b1)<<5)
mvn r11, r10 @ R11= NOT R10= 0x0000FFFF
and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a0+b0)>>11)
orr r8, r8, r9
str r8, [r14, #0]
add r8, r3, r5 @ R8=a2+b2
add r9, r4, r7 @ R9=a3+b3
and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a3+b3)<<5)
and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a2+b2)>>11)
orr r8, r8, r9
str r8, [r14, #4]
sub r8, r4, r7 @ R8=a3-b3
sub r9, r3, r5 @ R9=a2-b2
and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a2-b2)<<5)
and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a3-b3)>>11)
orr r8, r8, r9
str r8, [r14, #8]
sub r8, r2, r1 @ R8=a1-b1
sub r9, r6, r0 @ R9=a0-b0
and r9, r10, r9, lsl #ROW_SHIFT2MSHW @ R9=0xFFFF0000 & ((a0-b0)<<5)
and r8, r11, r8, asr #ROW_SHIFT @ R8=0x0000FFFF & ((a1-b1)>>11)
orr r8, r8, r9
str r8, [r14, #12]
bal __end_row_loop
__almost_empty_row:
@@ the row was empty, except ROWr16[0], now, management of this special case
@@ at this point, R0=block, R14=&block[n], R12=__const_ptr_, R1=ROWr32[0], R2=ROWr32[1],
@@ R3=ROWr32[2], R4=ROWr32[3], R5=(temp), R6=ROWr16[0], R7=ROWr16[1],
@@ R8=0xFFFF (temp), R9-R11 free
mov r8, #0x10000 @ R8=0xFFFF (2 steps needed!) it saves a ldr call (because of delay run).
sub r8, r8, #1 @ R8 is now ready.
and r5, r8, r6, lsl #3 @ R5=R8 & (R6<<3)= (ROWr16[0]<<3) & 0xFFFF
orr r5, r5, r5, lsl #16 @ R5=R5 | (R5<<16)
str r5, [r14, #0] @ R14[0]=ROWr32[0]=R5
str r5, [r14, #4] @ R14[4]=ROWr32[1]=R5
str r5, [r14, #8] @ R14[8]=ROWr32[2]=R5
str r5, [r14, #12] @ R14[12]=ROWr32[3]=R5
__end_row_loop:
@@ at this point, R0-R11 (free)
@@ R12=__const_ptr_, R14=&block[n]
ldr r0, [sp, #0] @ R0=block
teq r0, r14 @ compare current &block[8*n] to block, when block is reached, the loop is finished.
sub r14, r14, #16
bne __row_loop
@@ at this point, R0=block, R1-R11 (free)
@@ R12=__const_ptr_, R14=&block[n]
add r14, r0, #14 @ R14=&block[7], better start from the last col, and decrease the value until col=0, i.e. R14=block.
__col_loop:
__b_evaluation2:
@@ at this point, R0=block (temp), R1-R11 (free)
@@ R12=__const_ptr_, R14=&block[n]
@@ proceed with b0-b3 first, followed by a0-a3
@@ MUL16(b0, W1, col[8x1]);
@@ MUL16(b1, W3, col[8x1]);
@@ MUL16(b2, W5, col[8x1]);
@@ MUL16(b3, W7, col[8x1]);
@@ MAC16(b0, W3, col[8x3]);
@@ MAC16(b1, -W7, col[8x3]);
@@ MAC16(b2, -W1, col[8x3]);
@@ MAC16(b3, -W5, col[8x3]);
ldr r8, [r12, #offW1] @ R8=W1
ldrsh r7, [r14, #16]
mul r0, r8, r7 @ R0=W1*ROWr16[1]=b0 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
ldr r9, [r12, #offW3] @ R9=W3
ldr r10, [r12, #offW5] @ R10=W5
mul r1, r9, r7 @ R1=W3*ROWr16[1]=b1 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
ldr r11, [r12, #offW7] @ R11=W7
mul r5, r10, r7 @ R5=W5*ROWr16[1]=b2 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
ldrsh r2, [r14, #48]
mul r7, r11, r7 @ R7=W7*ROWr16[1]=b3 (ROWr16[1] must be the second arg, to have the possibility to save 1 cycle)
teq r2, #0 @ if 0, then avoid muls
mlane r0, r9, r2, r0 @ R0+=W3*ROWr16[3]=b0 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
rsbne r2, r2, #0 @ R2=-ROWr16[3]
mlane r1, r11, r2, r1 @ R1-=W7*ROWr16[3]=b1 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
mlane r5, r8, r2, r5 @ R5-=W1*ROWr16[3]=b2 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
mlane r7, r10, r2, r7 @ R7-=W5*ROWr16[3]=b3 (ROWr16[3] must be the second arg, to have the possibility to save 1 cycle)
@@ at this point, R0=b0, R1=b1, R2 (free), R3 (free), R4 (free),
@@ R5=b2, R6 (free), R7=b3, R8=W1, R9=W3, R10=W5, R11=W7,
@@ R12=__const_ptr_, R14=&block[n]
@@ MAC16(b0, W5, col[5x8]);
@@ MAC16(b2, W7, col[5x8]);
@@ MAC16(b3, W3, col[5x8]);
@@ MAC16(b1, -W1, col[5x8]);
@@ MAC16(b0, W7, col[7x8]);
@@ MAC16(b2, W3, col[7x8]);
@@ MAC16(b3, -W1, col[7x8]);
@@ MAC16(b1, -W5, col[7x8]);
ldrsh r3, [r14, #80] @ R3=COLr16[5x8]
teq r3, #0 @ if 0 then avoid muls
mlane r0, r10, r3, r0 @ R0+=W5*ROWr16[5x8]=b0
mlane r5, r11, r3, r5 @ R5+=W7*ROWr16[5x8]=b2
mlane r7, r9, r3, r7 @ R7+=W3*ROWr16[5x8]=b3
rsbne r3, r3, #0 @ R3=-ROWr16[5x8]
ldrsh r4, [r14, #112] @ R4=COLr16[7x8]
mlane r1, r8, r3, r1 @ R7-=W1*ROWr16[5x8]=b1
@@ R3 is free now
teq r4, #0 @ if 0 then avoid muls
mlane r0, r11, r4, r0 @ R0+=W7*ROWr16[7x8]=b0
mlane r5, r9, r4, r5 @ R5+=W3*ROWr16[7x8]=b2
rsbne r4, r4, #0 @ R4=-ROWr16[7x8]
mlane r7, r8, r4, r7 @ R7-=W1*ROWr16[7x8]=b3
mlane r1, r10, r4, r1 @ R1-=W5*ROWr16[7x8]=b1
@@ R4 is free now
__end_b_evaluation2:
@@ at this point, R0=b0, R1=b1, R2 (free), R3 (free), R4 (free),
@@ R5=b2, R6 (free), R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
__a_evaluation2:
@@ a0 = (W4 * col[8x0]) + (1 << (COL_SHIFT - 1));
@@ a1 = a0 + W6 * row[2];
@@ a2 = a0 - W6 * row[2];
@@ a3 = a0 - W2 * row[2];
@@ a0 = a0 + W2 * row[2];
ldrsh r6, [r14, #0]
ldr r9, [r12, #offW4] @ R9=W4
mul r6, r9, r6 @ R6=W4*ROWr16[0]
ldr r10, [r12, #offW6] @ R10=W6
ldrsh r4, [r14, #32] @ R4=ROWr16[2] (a3 not defined yet)
add r6, r6, #COL_SHIFTED_1 @ R6=W4*ROWr16[0] + 1<<(COL_SHIFT-1) (a0)
mul r11, r10, r4 @ R11=W6*ROWr16[2]
ldr r8, [r12, #offW2] @ R8=W2
add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
sub r3, r6, r11 @ R3=a0-W6*ROWr16[2] (a2)
mul r11, r8, r4 @ R11=W2*ROWr16[2]
sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
@@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
@@ R5=b2, R6=a0, R7=b3, R8=W2, R9=W4, R10=W6, R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
@@ a0 += W4*row[4]
@@ a1 -= W4*row[4]
@@ a2 -= W4*row[4]
@@ a3 += W4*row[4]
ldrsh r11, [r14, #64] @ R11=ROWr16[4]
teq r11, #0 @ if null avoid muls
mulne r11, r9, r11 @ R11=W4*ROWr16[4]
@@ R9 is free now
addne r6, r6, r11 @ R6+=W4*ROWr16[4] (a0)
subne r2, r2, r11 @ R2-=W4*ROWr16[4] (a1)
subne r3, r3, r11 @ R3-=W4*ROWr16[4] (a2)
ldrsh r9, [r14, #96] @ R9=ROWr16[6]
addne r4, r4, r11 @ R4+=W4*ROWr16[4] (a3)
@@ W6 alone is no more useful, save W2*ROWr16[6] in it instead
teq r9, #0 @ if null avoid muls
mulne r11, r10, r9 @ R11=W6*ROWr16[6]
addne r6, r6, r11 @ R6+=W6*ROWr16[6] (a0)
mulne r10, r8, r9 @ R10=W2*ROWr16[6]
@@ a0 += W6*row[6];
@@ a3 -= W6*row[6];
@@ a1 -= W2*row[6];
@@ a2 += W2*row[6];
subne r4, r4, r11 @ R4-=W6*ROWr16[6] (a3)
subne r2, r2, r10 @ R2-=W2*ROWr16[6] (a1)
addne r3, r3, r10 @ R3+=W2*ROWr16[6] (a2)
__end_a_evaluation2:
@@ at this point, R0=b0, R1=b1, R2=a1, R3=a2, R4=a3,
@@ R5=b2, R6=a0, R7=b3, R8 (free), R9 (free), R10 (free), R11 (free),
@@ R12=__const_ptr_, R14=&block[n]
@@ col[0 ] = ((a0 + b0) >> COL_SHIFT);
@@ col[8 ] = ((a1 + b1) >> COL_SHIFT);
@@ col[16] = ((a2 + b2) >> COL_SHIFT);
@@ col[24] = ((a3 + b3) >> COL_SHIFT);
@@ col[32] = ((a3 - b3) >> COL_SHIFT);
@@ col[40] = ((a2 - b2) >> COL_SHIFT);
@@ col[48] = ((a1 - b1) >> COL_SHIFT);
@@ col[56] = ((a0 - b0) >> COL_SHIFT);
@@@@@ no optimisation here @@@@@
add r8, r6, r0 @ R8=a0+b0
add r9, r2, r1 @ R9=a1+b1
mov r8, r8, asr #COL_SHIFT
mov r9, r9, asr #COL_SHIFT
strh r8, [r14, #0]
strh r9, [r14, #16]
add r8, r3, r5 @ R8=a2+b2
add r9, r4, r7 @ R9=a3+b3
mov r8, r8, asr #COL_SHIFT
mov r9, r9, asr #COL_SHIFT
strh r8, [r14, #32]
strh r9, [r14, #48]
sub r8, r4, r7 @ R8=a3-b3
sub r9, r3, r5 @ R9=a2-b2
mov r8, r8, asr #COL_SHIFT
mov r9, r9, asr #COL_SHIFT
strh r8, [r14, #64]
strh r9, [r14, #80]
sub r8, r2, r1 @ R8=a1-b1
sub r9, r6, r0 @ R9=a0-b0
mov r8, r8, asr #COL_SHIFT
mov r9, r9, asr #COL_SHIFT
strh r8, [r14, #96]
strh r9, [r14, #112]
__end_col_loop:
@@ at this point, R0-R11 (free)
@@ R12=__const_ptr_, R14=&block[n]
ldr r0, [sp, #0] @ R0=block
teq r0, r14 @ compare current &block[n] to block, when block is reached, the loop is finished.
sub r14, r14, #2
bne __col_loop
__end_simple_idct_ARM:
@@ restore registers to previous status!
add sp, sp, #8 @@ the local variables!
ldmfd sp!, {r4-r11, r15} @@ update PC with LR content.
@@ kind of sub-function, here not to overload the common case.
__end_bef_a_evaluation:
add r2, r6, r11 @ R2=a0+W6*ROWr16[2] (a1)
mul r11, r8, r4 @ R11=W2*ROWr16[2]
sub r4, r6, r11 @ R4=a0-W2*ROWr16[2] (a3)
add r6, r6, r11 @ R6=a0+W2*ROWr16[2] (a0)
bal __end_a_evaluation
__constant_ptr__: @@ see #defines at the beginning of the source code for values.
.align
.word W1
.word W2
.word W3
.word W4
.word W5
.word W6
.word W7
.word MASK_MSHW
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