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Extract to macro

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This commit is contained in:
Gwilym Kuiper 2022-04-26 21:04:33 +01:00
parent 61ed2b905d
commit 260f664c36
1 changed files with 13 additions and 9 deletions
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22
agb/src/sound/mixer/mixer.s
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@ -169,18 +169,22 @@ agb_arm_func agb_rs__mixer_collapse
mov r4, r2
1:
@ r12 = *r1; r1++
ldr r12, [r1], #4
.macro load_sample left_reg:req right_reg:req
@ left_reg = *r1; r1++
ldr \left_reg, [r1], #4
lsl r3, r12, #16 @ r3 is going to be the right sample, push r12 left 16 bits first
asr r3, r3, #20 @ move r3 back to being the correct value
mov r12, r12, asr #20 @ r12 = left sample
lsl \right_reg, \left_reg, #16 @ push the sample 16 bits first
asr \right_reg, \right_reg, #20 @ move right sample back to being the correct value
mov \left_reg, \left_reg, asr #20 @ now we only have the left sample
clamp_s8 r12 @ clamp the audio to 8 bit values
clamp_s8 r3
clamp_s8 \left_reg @ clamp the audio to 8 bit values
clamp_s8 \right_reg
.endm
strb r3, [r0, r4] @ *(r0 + r4 = SOUND_BUFFER_SIZE) = r3
strb r12, [r0], #1 @ *r0 = r12; r0++
load_sample r3, r12
strb r3, [r0, r4] @ *(r0 + (r4 = SOUND_BUFFER_SIZE)) = r3
strb r12, [r0], #1 @ *r0 = r12; r0++
subs r2, r2, #1 @ r2 -= 1
bne 1b @ loop if not 0