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Somehow reduce clamp_s8 by 1 instruction

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Gwilym Kuiper 2022-05-04 17:58:24 +01:00
parent 0229b95d7c
commit 3fea9aada0
1 changed files with 18 additions and 9 deletions
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27
agb/src/sound/mixer/mixer.s
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@ -155,19 +155,24 @@ agb_arm_func agb_rs__mixer_collapse
@ Arguments:
@ r0 = target buffer (i8)
@ r1 = input buffer (i16) of fixnums with 4 bits of precision (read in sets of i16 in an i32)
push {r4, r5, r6}
push {r4, r5, r6, r7, r8, r9, r10}
CONST_0 .req r7
CONST_FF .req r8
CONST_127 .req r9
TEMP .req r10
ldr CONST_0, =0
ldr CONST_FF, =0xff
ldr CONST_127, =127
ldr r2, agb_rs__buffer_size @ loop counter
mov r4, r2
.macro clamp_s8 reg:req
cmn \reg, #128
mvnlt \reg, #128
cmp \reg, #127
movgt \reg, #127
and \reg, \reg, #255
add \reg, \reg, #127
subs r10, r7, \reg, asr #8
andne \reg, r8, r10, lsr #24
.endm
.macro load_sample left_reg:req right_reg:req
@ -197,12 +202,16 @@ agb_arm_func agb_rs__mixer_collapse
orr r3, r3, r5, lsl #24
orr r12, r12, r6, lsl #24
ldr r5, =0x80808080
eor r3, r3, r5
eor r12, r12, r5
str r3, [r0, r4] @ *(r0 + (r4 = SOUND_BUFFER_SIZE)) = r3
str r12, [r0], #4 @ *r0 = r12; r0 += 4
subs r2, r2, #4 @ r2 -= 4
bne 1b @ loop if not 0
pop {r4, r5, r6}
pop {r4, r5, r6, r7, r8, r9, r10}
bx lr
agb_arm_end agb_rs__mixer_collapse