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authorMåns Rullgård <mans@mansr.com>2008-12-17 00:54:54 +0000
committerMåns Rullgård <mans@mansr.com>2008-12-17 00:54:54 +0000
commita2fc0f6a6ddf884ace3c96a0d4f09f0932e6db32 (patch)
tree44b807b924e29465a6aed924fcb53c719a83a956 /libavcodec/arm/simple_idct_arm.S
parent2600f8c86dcaa411a0485b1518e5e1592374aaf6 (diff)
ARM: replace "armv4l" with "arm"
Originally committed as revision 16179 to svn://svn.ffmpeg.org/ffmpeg/trunk
Diffstat (limited to 'libavcodec/arm/simple_idct_arm.S')
-rw-r--r--libavcodec/arm/simple_idct_arm.S486
1 files changed, 486 insertions, 0 deletions
diff --git a/libavcodec/arm/simple_idct_arm.S b/libavcodec/arm/simple_idct_arm.S
new file mode 100644
index 0000000000..16ade1f3da
--- /dev/null
+++ b/libavcodec/arm/simple_idct_arm.S
@@ -0,0 +1,486 @@
+/*
+ * simple_idct_arm.S
+ * Copyright (C) 2002 Frederic 'dilb' Boulay.
+ *
+ * Author: Frederic Boulay <dilb@handhelds.org>
+ *
+ * The function defined in this file is derived from the simple_idct function
+ * from the libavcodec library part of the FFmpeg project.
+ *
+ * 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
+ */
+
+#include "asm.S"
+
+/* 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
+
+function simple_idct_ARM, export=1
+ @@ 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 optimize 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 optimization 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