arm7: decompile SND_util

2 files changed, 91 insertions, 190 deletions

diff --git a/arm7/asm/SND_util.s b/arm7/asm/SND_util.s
deleted file mode 100644
index 7964fe4e..00000000
--- a/arm7/asm/SND_util.s
+++ /dev/null
@@ -1,190 +0,0 @@
-	.include "asm/macros.inc"
-	.include "global.inc"
-
-    .section .data
-
-	.global _03807660
-_03807660:
-	.word	0x12345678
-
-    .section .text
-
-	arm_func_start SND_CalcRandom
-SND_CalcRandom: ; 0x037FC058
-	ldr	r2, _037FC080	; =_03807660
-	ldr	r3, [r2]
-	ldr	r0, _037FC084	; =0x0019660D
-	ldr	r1, _037FC088	; =0x3C6EF35F
-	mla	r0, r3, r0, r1
-	str	r0, [r2]
-	mov	r0, r0, lsr #16
-	mov	r0, r0, lsl #16
-	mov	r0, r0, lsr #16
-	bx	lr
-_037FC080:	.word	_03807660
-_037FC084:	.word	0x0019660D
-_037FC088:	.word	0x3C6EF35F
-
-	arm_func_start SND_SinIdx
-SND_SinIdx: ; 0x037FC08C
-	cmp	r0, #32
-	ldrlt	r1, _037FC0F4	; =sLfoSinTable
-	ldrltsb	r0, [r1, r0]
-	bxlt	lr
-	cmp	r0, #64	; 0x40
-	rsblt	r1, r0, #64	; 0x40
-	ldrlt	r0, _037FC0F4	; =sLfoSinTable
-	ldrltsb	r0, [r0, r1]
-	bxlt	lr
-	cmp	r0, #96	; 0x60
-	bge	_037FC0D4
-	sub	r1, r0, #64	; 0x40
-	ldr	r0, _037FC0F4	; =sLfoSinTable
-	ldrsb	r0, [r0, r1]
-	rsb	r0, r0, #0
-	mov	r0, r0, lsl #24
-	mov	r0, r0, asr #24
-	bx	lr
-_037FC0D4:
-	sub	r0, r0, #96	; 0x60
-	rsb	r1, r0, #32
-	ldr	r0, _037FC0F4	; =sLfoSinTable
-	ldrsb	r0, [r0, r1]
-	rsb	r0, r0, #0
-	mov	r0, r0, lsl #24
-	mov	r0, r0, asr #24
-	bx	lr
-_037FC0F4:	.word	sLfoSinTable
-
-	arm_func_start SND_CalcChannelVolume
-SND_CalcChannelVolume: ; 0x037FC0F8
-	stmdb	sp!, {r4, lr}
-	mov	r4, r0
-	ldr	r0, _037FC168	; =0xFFFFFD2D
-	cmp	r4, r0
-	movlt	r4, r0
-	blt	_037FC118
-	cmp	r4, #0
-	movgt	r4, #0
-_037FC118:
-	ldr	r0, _037FC16C	; =0x000002D3
-	add	r0, r4, r0
-	bl	FUN_037FC170
-	mvn	r1, #239	; 0xef
-	cmp	r4, r1
-	movlt	r1, #3
-	blt	_037FC154
-	mvn	r1, #119	; 0x77
-	cmp	r4, r1
-	movlt	r1, #2
-	blt	_037FC154
-	mvn	r1, #59	; 0x3b
-	cmp	r4, r1
-	movlt	r1, #1
-	movge	r1, #0
-_037FC154:
-	orr	r0, r0, r1, lsl #8
-	mov	r0, r0, lsl #16
-	mov	r0, r0, lsr #16
-	ldmia	sp!, {r4, lr}
-	bx	lr
-_037FC168:	.word	0xFFFFFD2D
-_037FC16C:	.word	0x000002D3
-
-	arm_func_start FUN_037FC170
-FUN_037FC170: ; 0x037FC170
-	ldr	ip, _037FC178	; =SVC_GetVolumeTable
-	bx	ip
-_037FC178:	.word	SVC_GetVolumeTable
-
-	arm_func_start SND_CalcTimer
-SND_CalcTimer: ; 0x037FC17C
-	stmdb	sp!, {r4, r5, lr}
-	sub	sp, sp, #4
-	mov	r5, r0
-	mov	r4, #0
-	rsb	r0, r1, #0
-	b	_037FC19C
-_037FC194:
-	sub	r4, r4, #1
-	add	r0, r0, #768	; 0x300
-_037FC19C:
-	cmp	r0, #0
-	blt	_037FC194
-	b	_037FC1B0
-_037FC1A8:
-	add	r4, r4, #1
-	sub	r0, r0, #768	; 0x300
-_037FC1B0:
-	cmp	r0, #768	; 0x300
-	bge	_037FC1A8
-	bl	FUN_037FC2A4
-	mov	r2, #0
-	mov	r1, #65536	; 0x10000
-	adds	lr, r0, r1
-	adc	ip, r2, #0
-	mov	r3, r5, asr #31
-	umull	r1, r0, lr, r5
-	mla	r0, lr, r3, r0
-	mla	r0, ip, r5, r0
-	sub	lr, r4, #16
-	cmp	lr, #0
-	bgt	_037FC208
-	rsb	r2, lr, #0
-	mov	r3, r0, lsr r2
-	mov	r5, r1, lsr r2
-	rsb	r1, r2, #32
-	orr	r5, r5, r0, lsl r1
-	sub	r1, r2, #32
-	orr	r5, r5, r0, lsr r1
-	b	_037FC264
-_037FC208:
-	cmp	lr, #32
-	bge	_037FC25C
-	mvn	r5, #0
-	rsb	r4, lr, #32
-	mov	ip, r5, lsl r4
-	rsb	r3, r4, #32
-	orr	ip, ip, r5, lsr r3
-	sub	r3, r4, #32
-	orr	ip, ip, r5, lsl r3
-	and	r3, r0, ip
-	and	r5, r1, r5, lsl r4
-	cmp	r3, r2
-	cmpeq	r5, r2
-	ldrne	r0, _037FC2A0	; =0x0000FFFF
-	bne	_037FC294
-	mov	r5, r1, lsl lr
-	mov	r3, r0, lsl lr
-	orr	r3, r3, r1, lsr r4
-	sub	r0, lr, #32
-	orr	r3, r3, r1, lsl r0
-	b	_037FC264
-_037FC25C:
-	ldr	r0, _037FC2A0	; =0x0000FFFF
-	b	_037FC294
-_037FC264:
-	mov	r1, #0
-	mov	r0, #16
-	cmp	r3, r1
-	cmpeq	r5, r0
-	movcc	r5, r0
-	bcc	_037FC28C
-	ldr	r0, _037FC2A0	; =0x0000FFFF
-	cmp	r3, r1
-	cmpeq	r5, r0
-	movhi	r5, r0
-_037FC28C:
-	mov	r0, r5, lsl #16
-	mov	r0, r0, lsr #16
-_037FC294:
-	add	sp, sp, #4
-	ldmia	sp!, {r4, r5, lr}
-	bx	lr
-_037FC2A0:	.word	0x0000FFFF
-
-	arm_func_start FUN_037FC2A4
-FUN_037FC2A4: ; 0x037FC2A4
-	ldr	ip, _037FC2AC	; =SVC_GetPitchTable
-	bx	ip
-_037FC2AC:	.word	SVC_GetPitchTable
diff --git a/arm7/lib/src/SND_util.c b/arm7/lib/src/SND_util.c
new file mode 100644
index 00000000..6a939c02
--- /dev/null
+++ b/arm7/lib/src/SND_util.c
@@ -0,0 +1,91 @@
+#include "SND_util.h"
+
+#include "syscall.h"
+
+// TODO remove this extern once the static const definition of it is here
+extern s8 sLfoSinTable[0x21];
+
+u16 SND_CalcTimer(int timer, int pitch) {
+    int octave = 0;
+    int pitch_normalized = -pitch;
+
+    while (pitch_normalized < 0) {
+        octave--;
+        pitch_normalized += 768;
+    }
+
+    while (pitch_normalized >= 768) {
+        octave++;
+        pitch_normalized -= 768;
+    }
+
+    u64 result = SVC_GetPitchTable(pitch_normalized);
+
+    result += 0x10000;
+    result *= timer;
+    
+    int shift = octave - 16;
+
+    if (shift <= 0) {
+        shift = -shift;
+        result >>= shift;
+    } else if (shift < 32) {
+        // what ???
+        u64 tmp = result & ~0uLL << (32 - shift);
+        if (tmp != 0)
+            return 0xFFFF;
+        result <<= shift;
+    } else {
+        return 0xFFFF;
+    }
+
+    if (result < 0x10)
+        result = 0x10;
+    else if (result > 0xFFFF)
+        result = 0xFFFF;
+
+    return (u16)result;
+}
+
+u16 SND_CalcChannelVolume(int value) {
+    if (value < SND_VOL_DB_MIN)
+        value = SND_VOL_DB_MIN;
+    else if (value > 0)
+        value = 0;
+
+    int result = SVC_GetVolumeTable(value + (-SND_VOL_DB_MIN));
+    int div;
+
+    if (value < -240)
+        div = 3;
+    else if (value < -120)
+        div = 2;
+    else if (value < -60)
+        div = 1;
+    else
+        div = 0;
+
+    return (u16)(result | (div << 8));
+}
+
+s8 SND_SinIdx(int x) {
+    // BUG: UB for out of range values
+    
+    if (x < 0x20) {
+        return sLfoSinTable[x];
+    } else if (x < 0x40) {
+        return sLfoSinTable[0x40 - x];
+    } else if (x < 0x60) {
+        return (s8)(-sLfoSinTable[x - 0x40]);
+    } else {
+        return (s8)(-sLfoSinTable[0x20 - (x - 0x60)]);
+    }
+}
+
+u16 SND_CalcRandom(void) {
+    static u32 state = 0x12345678;
+
+    // values from "Numerical Recipes"
+    state = state * 1664525u + 1013904223u;
+    return (u16)(state >> 16u);
+}