diff --git a/src/game/data/data_000000.c b/src/game/data/data_000000.c
index 8655a7fd3..11a98884d 100644
--- a/src/game/data/data_000000.c
+++ b/src/game/data/data_000000.c
@@ -3042,7 +3042,7 @@ u32 var8005cf54 = 0x00000000;
 u32 var8005cf58 = 0x00000000;
 u32 var8005cf5c = 0x00000000;
 OSTime osClockRate = 62500000;
-u32 osViClock = VI_NTSC_CLOCK;
+s32 osViClock = VI_NTSC_CLOCK;
 u32 var8005cf6c = 0x00000000;
 u32 __osGlobalIntMask = 0x003fff01;
 u32 var8005cf74 = 0x00000000;
diff --git a/src/include/game/data/data_000000.h b/src/include/game/data/data_000000.h
index fdef4c3fd..813ce9621 100644
--- a/src/include/game/data/data_000000.h
+++ b/src/include/game/data/data_000000.h
@@ -58,7 +58,7 @@ extern u32 var8005cefc;
 extern OSDevMgr __osPiDevMgr;
 extern u32 var8005cf30;
 extern OSTime osClockRate;
-extern u32 osViClock;
+extern s32 osViClock;
 extern u32 var8005cf6c;
 extern u32 __osGlobalIntMask;
 extern u32 var8005cf84;
diff --git a/src/lib/ultra/io/aisetfreq.c b/src/lib/ultra/io/aisetfreq.c
index 75c8fe71c..b4114d8c1 100644
--- a/src/lib/ultra/io/aisetfreq.c
+++ b/src/lib/ultra/io/aisetfreq.c
@@ -1,97 +1,26 @@
 #include <ultra64.h>
+#include "game/data/data_000000.h"
 
-GLOBAL_ASM(
-glabel osAiSetFrequency
-/*    4e270:	3c058006 */ 	lui	$a1,%hi(osViClock)
-/*    4e274:	24a5cf68 */ 	addiu	$a1,$a1,%lo(osViClock)
-/*    4e278:	8cae0000 */ 	lw	$t6,0x0($a1)
-/*    4e27c:	44844000 */ 	mtc1	$a0,$f8
-/*    4e280:	3c014f80 */ 	lui	$at,0x4f80
-/*    4e284:	448e2000 */ 	mtc1	$t6,$f4
-/*    4e288:	468042a0 */ 	cvt.s.w	$f10,$f8
-/*    4e28c:	04810004 */ 	bgez	$a0,.L0004e2a0
-/*    4e290:	468021a0 */ 	cvt.s.w	$f6,$f4
-/*    4e294:	44818000 */ 	mtc1	$at,$f16
-/*    4e298:	00000000 */ 	nop
-/*    4e29c:	46105280 */ 	add.s	$f10,$f10,$f16
-.L0004e2a0:
-/*    4e2a0:	460a3483 */ 	div.s	$f18,$f6,$f10
-/*    4e2a4:	3c013f00 */ 	lui	$at,0x3f00
-/*    4e2a8:	44812000 */ 	mtc1	$at,$f4
-/*    4e2ac:	24030001 */ 	addiu	$v1,$zero,0x1
-/*    4e2b0:	3c014f00 */ 	lui	$at,0x4f00
-/*    4e2b4:	3c08a450 */ 	lui	$t0,0xa450
-/*    4e2b8:	3c0aa450 */ 	lui	$t2,0xa450
-/*    4e2bc:	46049000 */ 	add.s	$f0,$f18,$f4
-/*    4e2c0:	444ff800 */ 	cfc1	$t7,$31
-/*    4e2c4:	44c3f800 */ 	ctc1	$v1,$31
-/*    4e2c8:	00000000 */ 	nop
-/*    4e2cc:	46000224 */ 	cvt.w.s	$f8,$f0
-/*    4e2d0:	4443f800 */ 	cfc1	$v1,$31
-/*    4e2d4:	00000000 */ 	nop
-/*    4e2d8:	30630078 */ 	andi	$v1,$v1,0x78
-/*    4e2dc:	50600013 */ 	beqzl	$v1,.L0004e32c
-/*    4e2e0:	44034000 */ 	mfc1	$v1,$f8
-/*    4e2e4:	44814000 */ 	mtc1	$at,$f8
-/*    4e2e8:	24030001 */ 	addiu	$v1,$zero,0x1
-/*    4e2ec:	46080201 */ 	sub.s	$f8,$f0,$f8
-/*    4e2f0:	44c3f800 */ 	ctc1	$v1,$31
-/*    4e2f4:	00000000 */ 	nop
-/*    4e2f8:	46004224 */ 	cvt.w.s	$f8,$f8
-/*    4e2fc:	4443f800 */ 	cfc1	$v1,$31
-/*    4e300:	00000000 */ 	nop
-/*    4e304:	30630078 */ 	andi	$v1,$v1,0x78
-/*    4e308:	14600005 */ 	bnez	$v1,.L0004e320
-/*    4e30c:	00000000 */ 	nop
-/*    4e310:	44034000 */ 	mfc1	$v1,$f8
-/*    4e314:	3c018000 */ 	lui	$at,0x8000
-/*    4e318:	10000007 */ 	b	.L0004e338
-/*    4e31c:	00611825 */ 	or	$v1,$v1,$at
-.L0004e320:
-/*    4e320:	10000005 */ 	b	.L0004e338
-/*    4e324:	2403ffff */ 	addiu	$v1,$zero,-1
-/*    4e328:	44034000 */ 	mfc1	$v1,$f8
-.L0004e32c:
-/*    4e32c:	00000000 */ 	nop
-/*    4e330:	0460fffb */ 	bltz	$v1,.L0004e320
-/*    4e334:	00000000 */ 	nop
-.L0004e338:
-/*    4e338:	44cff800 */ 	ctc1	$t7,$31
-/*    4e33c:	2c610084 */ 	sltiu	$at,$v1,0x84
-/*    4e340:	10200003 */ 	beqz	$at,.L0004e350
-/*    4e344:	2479ffff */ 	addiu	$t9,$v1,-1
-/*    4e348:	03e00008 */ 	jr	$ra
-/*    4e34c:	2402ffff */ 	addiu	$v0,$zero,-1
-.L0004e350:
-/*    4e350:	24010042 */ 	addiu	$at,$zero,0x42
-/*    4e354:	0061001b */ 	divu	$zero,$v1,$at
-/*    4e358:	00001012 */ 	mflo	$v0
-/*    4e35c:	305800ff */ 	andi	$t8,$v0,0xff
-/*    4e360:	2b010011 */ 	slti	$at,$t8,0x11
-/*    4e364:	14200002 */ 	bnez	$at,.L0004e370
-/*    4e368:	304400ff */ 	andi	$a0,$v0,0xff
-/*    4e36c:	24040010 */ 	addiu	$a0,$zero,0x10
-.L0004e370:
-/*    4e370:	ad190010 */ 	sw	$t9,0x10($t0)
-/*    4e374:	2489ffff */ 	addiu	$t1,$a0,-1
-/*    4e378:	ad490014 */ 	sw	$t1,0x14($t2)
-/*    4e37c:	8cab0000 */ 	lw	$t3,0x0($a1)
-/*    4e380:	0163001a */ 	div	$zero,$t3,$v1
-/*    4e384:	00001012 */ 	mflo	$v0
-/*    4e388:	14600002 */ 	bnez	$v1,.L0004e394
-/*    4e38c:	00000000 */ 	nop
-/*    4e390:	0007000d */ 	break	0x7
-.L0004e394:
-/*    4e394:	2401ffff */ 	addiu	$at,$zero,-1
-/*    4e398:	14610004 */ 	bne	$v1,$at,.L0004e3ac
-/*    4e39c:	3c018000 */ 	lui	$at,0x8000
-/*    4e3a0:	15610002 */ 	bne	$t3,$at,.L0004e3ac
-/*    4e3a4:	00000000 */ 	nop
-/*    4e3a8:	0006000d */ 	break	0x6
-.L0004e3ac:
-/*    4e3ac:	03e00008 */ 	jr	$ra
-/*    4e3b0:	00000000 */ 	nop
-/*    4e3b4:	00000000 */ 	nop
-/*    4e3b8:	00000000 */ 	nop
-/*    4e3bc:	00000000 */ 	nop
-);
+s32 osAiSetFrequency(u32 frequency)
+{
+	register unsigned int dacRate;
+	register char bitRate;
+	register float f;
+	f = osViClock / (float)frequency + .5f;
+	dacRate = f;
+
+	if (dacRate < AI_MIN_DAC_RATE) {
+		return -1;
+	}
+
+	bitRate = dacRate / 66;
+
+	if (bitRate > AI_MAX_BIT_RATE) {
+		bitRate = AI_MAX_BIT_RATE;
+	}
+
+	IO_WRITE(AI_DACRATE_REG, dacRate - 1);
+	IO_WRITE(AI_BITRATE_REG, bitRate - 1);
+
+	return osViClock / (s32)dacRate;
+}