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ARM DSP: Get an instruction out of the crossfeed main loop and improve loads and interlocks for stacked vars.

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git-svn-id: svn://svn.rockbox.org/rockbox/trunk@25946 a1c6a512-1295-4272-9138-f99709370657
This commit is contained in:
Michael Sevakis 2010-05-11 10:22:23 +00:00
parent 51845b344b
commit 81bfa137b6
1 changed files with 6 additions and 6 deletions
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12
apps/dsp_arm.S
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@ -274,8 +274,9 @@ apply_crossfeed:
ldr r1, =crossfeed_data
ldmia r1!, { r4-r11 } @ load direct gain and filter data
add r12, r1, #13*4*2 @ calculate end of delay
stmdb sp!, { r0, r12 } @ stack count and end of delay adr
mov r12, r0 @ better to ldm delay + count later
add r0, r1, #13*4*2 @ calculate end of delay
stmdb sp!, { r0, r12 } @ stack end of delay adr and count
ldr r0, [r1, #13*4*2] @ fetch current delay line address
/* Register usage in loop:
@ -304,15 +305,14 @@ apply_crossfeed:
smlal r14, r1, r4, r12 @ acc += gain*x_r[n]
str r12, [r0], #4 @ save right input to delay line
mov r1, r1, lsl #1 @ fix format
ldmia sp, { r12, r14 } @ fetch delay line end addr and count from stack
str r1, [r3], #4 @ save result
ldr r12, [sp, #4] @ fetch delay line end addr from stack
cmp r0, r12 @ need to wrap to start of delay?
subeq r0, r0, #13*4*2 @ wrap back delay line ptr to start
ldr r1, [sp] @ fetch count from stack
subs r1, r1, #1 @ are we finished?
strne r1, [sp] @ nope, save count back to stack
subs r14, r14, #1 @ are we finished?
strne r14, [sp, #4] @ nope, save count back to stack
bne .cfloop
@ save data back to struct