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Attempt to support changing the volume of stereo sound

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This commit is contained in:
Gwilym Kuiper 2022-07-16 18:47:39 +01:00
parent 3d579390c8
commit a5e0e145d2
2 changed files with 11 additions and 4 deletions
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8
agb/src/sound/mixer/mixer.s
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@ -95,10 +95,12 @@ agb_arm_func agb_rs__mixer_add_stereo
@ Arguments
@ r0 - pointer to the data to be copied (u8 array)
@ r1 - pointer to the sound buffer (i16 array which will alternate left and right channels, 32-bit aligned)
@ r2 - volume to play the sound at
@
@ The sound buffer must be SOUND_BUFFER_SIZE * 2 in size = 176 * 2
push {r4-r8}
push {r4-r9}
mov r9, r2
ldr r5, =0x00000FFF
ldr r8, =agb_rs__buffer_size
@ -128,7 +130,7 @@ agb_arm_func agb_rs__mixer_add_stereo
lsl r6, r6, #24 @ r6 = | R | 0 | 0 | 0 | drop everything except the right sample
orr r6, r7, r6, asr #8 @ r6 = | 1 | R | 1 | L | now we have it perfectly set up
add r4, r4, r6, lsl #4 @ r4 += r6 << 4 (calculating both the left and right samples together)
mla r4, r6, r9, r4 @ r4 += r6 * r9 (calculating both the left and right samples together)
str r4, [r1], #4 @ store the new value, and increment the pointer
.endr
@ -136,7 +138,7 @@ agb_arm_func agb_rs__mixer_add_stereo
subs r8, r8, #4 @ loop counter
bne 1b @ jump back if we're done with the loop
pop {r4-r8}
pop {r4-r9}
bx lr
agb_arm_end agb_rs__mixer_add_stereo

7
agb/src/sound/mixer/sw_mixer.rs
View file

@ -25,7 +25,11 @@ extern "C" {
right_amount: Num<i16, 4>,
);
fn agb_rs__mixer_add_stereo(sound_data: *const u8, sound_buffer: *mut Num<i16, 4>);
fn agb_rs__mixer_add_stereo(
sound_data: *const u8,
sound_buffer: *mut Num<i16, 4>,
volume: Num<i16, 4>,
);
fn agb_rs__mixer_collapse(sound_buffer: *mut i8, input_buffer: *const Num<i16, 4>);
}
@ -447,6 +451,7 @@ impl MixerBuffer {
agb_rs__mixer_add_stereo(
channel.data.as_ptr().add(channel.pos.floor()),
buffer.as_mut_ptr(),
channel.volume,
);
}
} else {