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Reduce the number of registers stored and used

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Gwilym Kuiper 2021-08-15 23:00:17 +01:00
parent 1be6dfbf36
commit a2f0c43f26
1 changed files with 5 additions and 5 deletions
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10
agb/src/sound/mixer/mixer.s
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@ -9,11 +9,11 @@ agb_arm_func agb_rs__mixer_add
@ stack position 1 - amount to modify the right channel by (u16 fixnum with 4 bits)
@
@ The sound buffer must be SOUND_BUFFER_SIZE * 2 in size = 176 * 2
push {r4-r10}
push {r4-r8}
ldr r9, [sp, #28] @ load the right channel modification amount into r9
ldr r7, [sp, #20] @ load the right channel modification amount into r7
orr r9, r9, r3, lsl #16 @ r9 now is the left channel followed by the right channel modifications.
orr r7, r7, r3, lsl #16 @ r7 now is the left channel followed by the right channel modifications.
mov r5, #0 @ current index we're reading from
mov r8, #SOUND_BUFFER_SIZE @ the number of steps left
@ -26,7 +26,7 @@ agb_arm_func agb_rs__mixer_add
ldr r4, [r1] @ read the current value
mla r4, r6, r9, r4 @ r4 += r6 * r9 (calculating both the left and right samples together)
mla r4, r6, r7, r4 @ r4 += r6 * r7 (calculating both the left and right samples together)
str r4, [r1], #4 @ store the new value, and increment the pointer
.endm
@ -39,7 +39,7 @@ agb_arm_func agb_rs__mixer_add
subs r8, r8, #4 @ loop counter
bne 1b @ jump back if we're done with the loop
pop {r4-r10}
pop {r4-r8}
bx lr
agb_arm_end agb_rs__mixer_add