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Extract a function to do the clearing of the buffer

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Gwilym Kuiper 2022-06-12 17:26:16 +01:00
parent 4969672c73
commit 2ace226db8
1 changed files with 28 additions and 15 deletions
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43
agb/src/sound/mixer/mixer.s
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@ -143,26 +143,39 @@ constant_zero:
.word 0
.endr
agb_arm_func agb_rs__init_buffer
@ arguments:
@ r0 = target buffer
@ r1 = size in bytes (must be a multiple of 16)
push {r4-r5}
@ zero registers r3-r5
mov r2, #constant_zero
ldm r2, {r3-r5,r12}
1:
@ zero 4 words worth of the buffer
stmia r0, {r3-r5,r12}
subs r1, r1, #16
@ loop if we haven't zeroed everything
bne 1b
pop {r4-r5}
bx lr
agb_arm_end agb_rs__init_buffer
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-r11}
@ zero registers r4-r7 (4 of them)
mov r8, #constant_zero
ldm r8, {r4-r7}
@ firstly clear the buffer
push {r0, r1, r4-r11, lr}
ldr r1, agb_rs__buffer_size
@ get the size of the buffer
ldr r9, agb_rs__buffer_size
@ make a copy of the output buffer pointer
mov r10, r0
1:
@ zero 4 words worth of the output buffer
stmia r10, {r4-r7}
subs r9, r9, #16
@ loop if we haven't zeroed everything
bne 1b
bl agb_rs__init_buffer
pop {r0, r1}
CONST_0 .req r7
CONST_FF .req r8
@ -239,6 +252,6 @@ SWAP_SIGN .req r11
subs r2, r2, #16 @ r2 -= 16
bne 1b @ loop if not 0
pop {r4-r11}
pop {r4-r11, lr}
bx lr
agb_arm_end agb_rs__mixer_collapse