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Rerrange some registers in butterfly_generic to combine some 2-word stores into 4-word stores and remove some redundant mov instructions. Shave off some additional instructions (stacking and additions) in butterfly_32 by getting butterfly_8 and butterfly_16 to do the address incrementing for us. Add a few comments.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@22525 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Dave Hooper 2009-08-29 11:50:15 +00:00
parent eeb1594494
commit 59cdbf5efc
1 changed files with 69 additions and 61 deletions
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130
apps/codecs/lib/mdct_arm.S
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@ -38,6 +38,9 @@
.global mdct_butterfly_generic_loop
mdct_butterfly_8:
@ inputs: r0,r1,r2,r3,r4,r5,r6,r10,r11 &lr
@ uses: r8,r9,r12(scratch)
@ modifies: r0,r1,r2,r3,r4,r5,r6,r10,r11. increments r0 by #8*4
add r9, r5, r1 @ x4 + x0
sub r5, r5, r1 @ x4 - x0
add r7, r6, r2 @ x5 + x1
@ -55,11 +58,15 @@ mdct_butterfly_8:
sub r6, r12, r7 @ y5 = (x7 + x3) - (x5 + x1)
add r10, r8, r9 @ y6 = (x6 + x2) + (x4 + x0)
add r11, r12, r7 @ y7 = (x7 + x3) + (x5 + x1)
stmia r0, {r1, r2, r3, r4, r5, r6, r10, r11}
stmia r0!, {r1, r2, r3, r4, r5, r6, r10, r11}
mov pc, lr
mdct_butterfly_16:
@ inputs: r0,r1 &lr
@ uses: r2,r3,r4,r5,r6,r7,r8,r9,r10,r11,r12
@ modifies: r0. increments r0 by #16*4
@ calls mdct_butterfly_8 via bl so need to stack lr for return address
str lr, [sp, #-4]!
add r1, r0, #8*4
@ -112,9 +119,13 @@ mdct_butterfly_16:
sub r0, r0, #4*4
ldmia r0, {r1, r2, r3, r4}
bl mdct_butterfly_8
add r0, r0, #8*4
@ mdct_butterfly_8 will have incremented r0 by #8*4 already
ldmia r0, {r1, r2, r3, r4, r5, r6, r10, r11}
bl mdct_butterfly_8
@ mdct_butterfly_8 increments r0 by another #8*4 here
@ at end, r0 has been incremented by #16*4
ldr pc, [sp], #4
@ -164,23 +175,23 @@ mdct_butterfly_32:
add r7, r7, r3 @ y21 = x21 + x5
rsb r3, r7, r3, asl #1 @ x5 - x21
add r8, r8, r4 @ y22 = x22 + x6
sub r4, r8, r4, asl #1 @ x22 - x6
sub r11, r8, r4, asl #1 @ x22 - x6
add r9, r9, r5 @ y23 = x23 + x7
rsb r5, r9, r5, asl #1 @ x7 - x23
rsb r10, r9, r5, asl #1 @ x7 - x23
stmia r1!, {r6, r7, r8, r9}
smull r10, r6, lr, r2
@r4,r5,r6,r7,r8,r9 now free
@ we don't use r5, r8, r9 below
smull r4, r6, lr, r2
rsb r2, r2, #0
smlal r10, r6, r12, r3
smull r10, r7, lr, r3
smlal r10, r7, r12, r2
smlal r4, r6, r12, r3
smull r4, r7, lr, r3
smlal r4, r7, r12, r2
mov r6, r6, asl #1
mov r7, r7, asl #1
mov r8, r5
mov r9, r4
stmia r0!, {r6, r7, r8, r9}
stmia r0!, {r6, r7, r10, r11}
ldmia r0, {r2, r3, r4, r5}
ldmia r1, {r6, r7, r8, r9}
@ -221,30 +232,29 @@ mdct_butterfly_32:
add r7, r7, r3 @ y29 = x29 + x13
sub r3, r7, r3, asl #1 @ x29 - x13
add r8, r8, r4 @ y30 = x30 + x14
sub r4, r8, r4, asl #1 @ x30 - x14
sub r10, r8, r4, asl #1 @ x30 - x14
add r9, r9, r5 @ y31 = x31 + x15
sub r5, r9, r5, asl #1 @ x31 - x15
sub r11, r9, r5, asl #1 @ x31 - x15
stmia r1, {r6, r7, r8, r9}
smull r10, r7, r12, r3
@ r4,r5,r6,r7,r8,r9 now free
@ we don't use r5,r8,r9 below
smull r4, r7, r12, r3
rsb r3, r3, #0
smlal r10, r7, lr, r2
smull r10, r6, lr, r3
smlal r10, r6, r12, r2
smlal r4, r7, lr, r2
smull r4, r6, lr, r3
smlal r4, r6, r12, r2
mov r6, r6, asl #1
mov r7, r7, asl #1
mov r8, r4
mov r9, r5
stmia r0, {r6, r7, r8, r9}
stmia r0, {r6, r7, r10, r11}
sub r0, r0, #12*4
str r0, [sp, #-4]!
bl mdct_butterfly_16
ldr r0, [sp], #4
add r0, r0, #16*4
@ we know mdct_butterfly_16 increments r0 by #16*4
@ and we wanted to advance by #16*4 anyway, so just call again
bl mdct_butterfly_16
ldmia sp!, {r4-r11, pc}
@ -278,19 +288,18 @@ mdct_butterfly_generic_loop:
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
add r2, r2, r3, asl #2
ldmia r2, {r6, r7}
smull r5, r8, r6, r11
ldmia r2, {r12, r14}
smull r5, r6, r12, r11
rsb r11, r11, #0
smlal r5, r8, r7, r10
smull r5, r9, r6, r10
smlal r5, r9, r7, r11
smlal r5, r6, r14, r10
smull r5, r7, r12, r10
smlal r5, r7, r14, r11
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
mov r6, r6, asl #1
mov r7, r7, asl #1
stmdb r1!, {r6, r7, r8, r9}
add r2, r2, r3, asl #2
cmp r2, r4
@ -321,19 +330,19 @@ mdct_butterfly_generic_loop:
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
sub r2, r2, r3, asl #2
ldmia r2, {r6, r7}
smull r5, r9, r6, r11
ldmia r2, {r12, r14}
smull r5, r7, r12, r11
rsb r11, r11, #0
smlal r5, r9, r7, r10
smull r5, r8, r6, r10
smlal r5, r8, r7, r11
smlal r5, r7, r14, r10
smull r5, r6, r12, r10
smlal r5, r6, r14, r11
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
mov r6, r6, asl #1
mov r7, r7, asl #1
stmdb r1!, {r6, r7, r8, r9}
sub r2, r2, r3, asl #2
cmp r2, r4
@ -364,19 +373,19 @@ mdct_butterfly_generic_loop:
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
add r2, r2, r3, asl #2
ldmia r2, {r6, r7}
smull r5, r8, r6, r10
ldmia r2, {r12, r14}
smull r5, r6, r12, r10
rsb r10, r10, #0
smlal r5, r8, r7, r11
smull r5, r9, r6, r11
smlal r5, r9, r7, r10
smlal r5, r6, r14, r11
smull r5, r7, r12, r11
smlal r5, r7, r14, r10
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
mov r6, r6, asl #1
mov r7, r7, asl #1
stmdb r1!, {r6, r7, r8, r9}
add r2, r2, r3, asl #2
cmp r2, r4
@ -407,19 +416,18 @@ mdct_butterfly_generic_loop:
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
sub r2, r2, r3, asl #2
ldmia r2, {r6, r7}
smull r5, r9, r6, r10
ldmia r2, {r12, r14}
smull r5, r7, r12, r10
rsb r10, r10, #0
smlal r5, r9, r7, r11
smull r5, r8, r6, r11
smlal r5, r8, r7, r10
smlal r5, r7, r14, r11
smull r5, r6, r12, r11
smlal r5, r6, r14, r10
mov r8, r8, asl #1
mov r9, r9, asl #1
stmdb r1!, {r8, r9}
mov r6, r6, asl #1
mov r7, r7, asl #1
stmdb r1!, {r6, r7, r8, r9}
sub r2, r2, r3, asl #2
cmp r2, r4