diff --git a/src/include/PR/os_vi.h b/src/include/PR/os_vi.h
index abfb9ce80..3227e7d8e 100644
--- a/src/include/PR/os_vi.h
+++ b/src/include/PR/os_vi.h
@@ -69,12 +69,25 @@
 #define OS_VI_UNK200 0x200
 #define OS_VI_UNK100 0x100
 
+#define VI_STATE_01             0x01
+#define VI_STATE_XSCALE_UPDATED 0x02
+#define VI_STATE_YSCALE_UPDATED 0x04
+#define VI_STATE_08             0x08
+#define VI_STATE_10             0x10
+#define VI_STATE_BLACK          0x20
+#define VI_STATE_REPEATLINE     0x40
+#define VI_STATE_FADE           0x80
+
 #define VI_STATE_BLACK 0x20
 
 #define VI_CTRL_ANTIALIAS_MODE_3 0x00300 /* Bit [9:8] anti-alias mode */
 #define VI_CTRL_ANTIALIAS_MODE_2 0x00200 /* Bit [9:8] anti-alias mode */
 #define VI_CTRL_ANTIALIAS_MODE_1 0x00100 /* Bit [9:8] anti-alias mode */
 
+#define VI_SCALE_MASK      0xfff
+#define VI_2_10_FPART_MASK 0x3ff
+#define VI_SUBPIXEL_SH     0x10
+
 #define BURST(hsync_width, color_width, vsync_width, color_start) \
     (hsync_width | (color_width << 8) | (vsync_width << 16) | (color_start << 20))
 #define WIDTH(v) v
diff --git a/src/include/game/data/data_000000.h b/src/include/game/data/data_000000.h
index f445356b0..d4d8308c3 100644
--- a/src/include/game/data/data_000000.h
+++ b/src/include/game/data/data_000000.h
@@ -51,6 +51,7 @@ extern u32 var8005ce9c;
 extern OSMesg var8005cea8;
 extern s8 var8005ced0;
 extern u32 __osViDevMgr;
+extern u32 var8005cefc;
 extern u32 __osPiDevMgr;
 extern u32 var8005cf30;
 extern u32 var8005cf60;
diff --git a/src/lib/ultra/io/viswapcontext.c b/src/lib/ultra/io/viswapcontext.c
index 5b0516839..4e3d3ac01 100644
--- a/src/lib/ultra/io/viswapcontext.c
+++ b/src/lib/ultra/io/viswapcontext.c
@@ -1,209 +1,70 @@
 #include <libultra_internal.h>
+#include "game/data/data_000000.h"
 
-GLOBAL_ASM(
-glabel __osViSwapContext
-/*    49790:	27bdffb8 */ 	addiu	$sp,$sp,-72
-/*    49794:	afb00018 */ 	sw	$s0,0x18($sp)
-/*    49798:	afbf001c */ 	sw	$ra,0x1c($sp)
-/*    4979c:	3c108006 */ 	lui	$s0,%hi(__osViNext)
-/*    497a0:	3c0ea440 */ 	lui	$t6,0xa440
-/*    497a4:	8e100914 */ 	lw	$s0,%lo(__osViNext)($s0)
-/*    497a8:	8dcf0010 */ 	lw	$t7,0x10($t6)
-/*    497ac:	8e050008 */ 	lw	$a1,0x8($s0)
-/*    497b0:	31f80001 */ 	andi	$t8,$t7,0x1
-/*    497b4:	afb8002c */ 	sw	$t8,0x2c($sp)
-/*    497b8:	8e040004 */ 	lw	$a0,0x4($s0)
-/*    497bc:	0c012d20 */ 	jal	osVirtualToPhysical
-/*    497c0:	afa50044 */ 	sw	$a1,0x44($sp)
-/*    497c4:	8fb9002c */ 	lw	$t9,0x2c($sp)
-/*    497c8:	8fa50044 */ 	lw	$a1,0x44($sp)
-/*    497cc:	960a0000 */ 	lhu	$t2,0x0($s0)
-/*    497d0:	00194080 */ 	sll	$t0,$t9,0x2
-/*    497d4:	01194021 */ 	addu	$t0,$t0,$t9
-/*    497d8:	00084080 */ 	sll	$t0,$t0,0x2
-/*    497dc:	00a83021 */ 	addu	$a2,$a1,$t0
-/*    497e0:	8cc90028 */ 	lw	$t1,0x28($a2)
-/*    497e4:	314b0002 */ 	andi	$t3,$t2,0x2
-/*    497e8:	11600008 */ 	beqz	$t3,.L0004980c
-/*    497ec:	01222021 */ 	addu	$a0,$t1,$v0
-/*    497f0:	8cad0020 */ 	lw	$t5,0x20($a1)
-/*    497f4:	8e0c0020 */ 	lw	$t4,0x20($s0)
-/*    497f8:	2401f000 */ 	addiu	$at,$zero,-4096
-/*    497fc:	01a17024 */ 	and	$t6,$t5,$at
-/*    49800:	018e7825 */ 	or	$t7,$t4,$t6
-/*    49804:	10000003 */ 	b	.L00049814
-/*    49808:	ae0f0020 */ 	sw	$t7,0x20($s0)
-.L0004980c:
-/*    4980c:	8cb80020 */ 	lw	$t8,0x20($a1)
-/*    49810:	ae180020 */ 	sw	$t8,0x20($s0)
-.L00049814:
-/*    49814:	96190000 */ 	lhu	$t9,0x0($s0)
-/*    49818:	33280004 */ 	andi	$t0,$t9,0x4
-/*    4981c:	51000035 */ 	beqzl	$t0,.L000498f4
-/*    49820:	8cce002c */ 	lw	$t6,0x2c($a2)
-/*    49824:	8cc3002c */ 	lw	$v1,0x2c($a2)
-/*    49828:	c6040024 */ 	lwc1	$f4,0x24($s0)
-/*    4982c:	3c014f80 */ 	lui	$at,0x4f80
-/*    49830:	30690fff */ 	andi	$t1,$v1,0xfff
-/*    49834:	44893000 */ 	mtc1	$t1,$f6
-/*    49838:	05210004 */ 	bgez	$t1,.L0004984c
-/*    4983c:	46803220 */ 	cvt.s.w	$f8,$f6
-/*    49840:	44815000 */ 	mtc1	$at,$f10
-/*    49844:	00000000 */ 	nop
-/*    49848:	460a4200 */ 	add.s	$f8,$f8,$f10
-.L0004984c:
-/*    4984c:	46082402 */ 	mul.s	$f16,$f4,$f8
-/*    49850:	24020001 */ 	addiu	$v0,$zero,0x1
-/*    49854:	3c014f00 */ 	lui	$at,0x4f00
-/*    49858:	444af800 */ 	cfc1	$t2,$31
-/*    4985c:	44c2f800 */ 	ctc1	$v0,$31
-/*    49860:	00000000 */ 	nop
-/*    49864:	460084a4 */ 	cvt.w.s	$f18,$f16
-/*    49868:	4442f800 */ 	cfc1	$v0,$31
-/*    4986c:	00000000 */ 	nop
-/*    49870:	30420078 */ 	andi	$v0,$v0,0x78
-/*    49874:	50400013 */ 	beqzl	$v0,.L000498c4
-/*    49878:	44029000 */ 	mfc1	$v0,$f18
-/*    4987c:	44819000 */ 	mtc1	$at,$f18
-/*    49880:	24020001 */ 	addiu	$v0,$zero,0x1
-/*    49884:	46128481 */ 	sub.s	$f18,$f16,$f18
-/*    49888:	44c2f800 */ 	ctc1	$v0,$31
-/*    4988c:	00000000 */ 	nop
-/*    49890:	460094a4 */ 	cvt.w.s	$f18,$f18
-/*    49894:	4442f800 */ 	cfc1	$v0,$31
-/*    49898:	00000000 */ 	nop
-/*    4989c:	30420078 */ 	andi	$v0,$v0,0x78
-/*    498a0:	14400005 */ 	bnez	$v0,.L000498b8
-/*    498a4:	00000000 */ 	nop
-/*    498a8:	44029000 */ 	mfc1	$v0,$f18
-/*    498ac:	3c018000 */ 	lui	$at,0x8000
-/*    498b0:	10000007 */ 	b	.L000498d0
-/*    498b4:	00411025 */ 	or	$v0,$v0,$at
-.L000498b8:
-/*    498b8:	10000005 */ 	b	.L000498d0
-/*    498bc:	2402ffff */ 	addiu	$v0,$zero,-1
-/*    498c0:	44029000 */ 	mfc1	$v0,$f18
-.L000498c4:
-/*    498c4:	00000000 */ 	nop
-/*    498c8:	0440fffb */ 	bltz	$v0,.L000498b8
-/*    498cc:	00000000 */ 	nop
-.L000498d0:
-/*    498d0:	ae02002c */ 	sw	$v0,0x2c($s0)
-/*    498d4:	8ccb002c */ 	lw	$t3,0x2c($a2)
-/*    498d8:	2401f000 */ 	addiu	$at,$zero,-4096
-/*    498dc:	44caf800 */ 	ctc1	$t2,$31
-/*    498e0:	01616824 */ 	and	$t5,$t3,$at
-/*    498e4:	004d6025 */ 	or	$t4,$v0,$t5
-/*    498e8:	10000003 */ 	b	.L000498f8
-/*    498ec:	ae0c002c */ 	sw	$t4,0x2c($s0)
-/*    498f0:	8cce002c */ 	lw	$t6,0x2c($a2)
-.L000498f4:
-/*    498f4:	ae0e002c */ 	sw	$t6,0x2c($s0)
-.L000498f8:
-/*    498f8:	3c028006 */ 	lui	$v0,%hi(var8005cefc)
-/*    498fc:	8c42cefc */ 	lw	$v0,%lo(var8005cefc)($v0)
-/*    49900:	8ccf0030 */ 	lw	$t7,0x30($a2)
-/*    49904:	0002c400 */ 	sll	$t8,$v0,0x10
-/*    49908:	01f8c823 */ 	subu	$t9,$t7,$t8
-/*    4990c:	03224021 */ 	addu	$t0,$t9,$v0
-/*    49910:	afa80034 */ 	sw	$t0,0x34($sp)
-/*    49914:	96030000 */ 	lhu	$v1,0x0($s0)
-/*    49918:	8ca7001c */ 	lw	$a3,0x1c($a1)
-/*    4991c:	30690020 */ 	andi	$t1,$v1,0x20
-/*    49920:	11200002 */ 	beqz	$t1,.L0004992c
-/*    49924:	306a0040 */ 	andi	$t2,$v1,0x40
-/*    49928:	00003825 */ 	or	$a3,$zero,$zero
-.L0004992c:
-/*    4992c:	5140000d */ 	beqzl	$t2,.L00049964
-/*    49930:	306b0080 */ 	andi	$t3,$v1,0x80
-/*    49934:	ae00002c */ 	sw	$zero,0x2c($s0)
-/*    49938:	8e040004 */ 	lw	$a0,0x4($s0)
-/*    4993c:	afa70038 */ 	sw	$a3,0x38($sp)
-/*    49940:	afa60024 */ 	sw	$a2,0x24($sp)
-/*    49944:	0c012d20 */ 	jal	osVirtualToPhysical
-/*    49948:	afa50044 */ 	sw	$a1,0x44($sp)
-/*    4994c:	8fa50044 */ 	lw	$a1,0x44($sp)
-/*    49950:	8fa60024 */ 	lw	$a2,0x24($sp)
-/*    49954:	8fa70038 */ 	lw	$a3,0x38($sp)
-/*    49958:	00402025 */ 	or	$a0,$v0,$zero
-/*    4995c:	96030000 */ 	lhu	$v1,0x0($s0)
-/*    49960:	306b0080 */ 	andi	$t3,$v1,0x80
-.L00049964:
-/*    49964:	51600010 */ 	beqzl	$t3,.L000499a8
-/*    49968:	3c0fa440 */ 	lui	$t7,0xa440
-/*    4996c:	960d0028 */ 	lhu	$t5,0x28($s0)
-/*    49970:	3c0103ff */ 	lui	$at,0x3ff
-/*    49974:	8e040004 */ 	lw	$a0,0x4($s0)
-/*    49978:	000d6400 */ 	sll	$t4,$t5,0x10
-/*    4997c:	01817024 */ 	and	$t6,$t4,$at
-/*    49980:	ae0e002c */ 	sw	$t6,0x2c($s0)
-/*    49984:	afa70038 */ 	sw	$a3,0x38($sp)
-/*    49988:	afa60024 */ 	sw	$a2,0x24($sp)
-/*    4998c:	0c012d20 */ 	jal	osVirtualToPhysical
-/*    49990:	afa50044 */ 	sw	$a1,0x44($sp)
-/*    49994:	8fa50044 */ 	lw	$a1,0x44($sp)
-/*    49998:	8fa60024 */ 	lw	$a2,0x24($sp)
-/*    4999c:	8fa70038 */ 	lw	$a3,0x38($sp)
-/*    499a0:	00402025 */ 	or	$a0,$v0,$zero
-/*    499a4:	3c0fa440 */ 	lui	$t7,0xa440
-.L000499a8:
-/*    499a8:	ade40004 */ 	sw	$a0,0x4($t7)
-/*    499ac:	8cb80008 */ 	lw	$t8,0x8($a1)
-/*    499b0:	3c19a440 */ 	lui	$t9,0xa440
-/*    499b4:	3c09a440 */ 	lui	$t1,0xa440
-/*    499b8:	af380008 */ 	sw	$t8,0x8($t9)
-/*    499bc:	8ca8000c */ 	lw	$t0,0xc($a1)
-/*    499c0:	3c0ba440 */ 	lui	$t3,0xa440
-/*    499c4:	3c0ca440 */ 	lui	$t4,0xa440
-/*    499c8:	ad280014 */ 	sw	$t0,0x14($t1)
-/*    499cc:	8caa0010 */ 	lw	$t2,0x10($a1)
-/*    499d0:	3c18a440 */ 	lui	$t8,0xa440
-/*    499d4:	3c08a440 */ 	lui	$t0,0xa440
-/*    499d8:	ad6a0018 */ 	sw	$t2,0x18($t3)
-/*    499dc:	8cad0014 */ 	lw	$t5,0x14($a1)
-/*    499e0:	3c0aa440 */ 	lui	$t2,0xa440
-/*    499e4:	3c028006 */ 	lui	$v0,%hi(__osViCurr)
-/*    499e8:	ad8d001c */ 	sw	$t5,0x1c($t4)
-/*    499ec:	8cae0018 */ 	lw	$t6,0x18($a1)
-/*    499f0:	3c0da440 */ 	lui	$t5,0xa440
-/*    499f4:	24420910 */ 	addiu	$v0,$v0,%lo(__osViCurr)
-/*    499f8:	adee0020 */ 	sw	$t6,0x20($t7)
-/*    499fc:	af070024 */ 	sw	$a3,0x24($t8)
-/*    49a00:	8fb90034 */ 	lw	$t9,0x34($sp)
-/*    49a04:	3c0ea440 */ 	lui	$t6,0xa440
-/*    49a08:	3c038006 */ 	lui	$v1,%hi(__osViNext)
-/*    49a0c:	ad190028 */ 	sw	$t9,0x28($t0)
-/*    49a10:	8cc90034 */ 	lw	$t1,0x34($a2)
-/*    49a14:	24630914 */ 	addiu	$v1,$v1,%lo(__osViNext)
-/*    49a18:	ad49002c */ 	sw	$t1,0x2c($t2)
-/*    49a1c:	8ccb0038 */ 	lw	$t3,0x38($a2)
-/*    49a20:	adab000c */ 	sw	$t3,0xc($t5)
-/*    49a24:	8e0c0020 */ 	lw	$t4,0x20($s0)
-/*    49a28:	02005825 */ 	or	$t3,$s0,$zero
-/*    49a2c:	adcc0030 */ 	sw	$t4,0x30($t6)
-/*    49a30:	8e0f002c */ 	lw	$t7,0x2c($s0)
-/*    49a34:	260c0030 */ 	addiu	$t4,$s0,0x30
-/*    49a38:	af0f0034 */ 	sw	$t7,0x34($t8)
-/*    49a3c:	8e19000c */ 	lw	$t9,0xc($s0)
-/*    49a40:	ad190000 */ 	sw	$t9,0x0($t0)
-/*    49a44:	8c4a0000 */ 	lw	$t2,0x0($v0)
-/*    49a48:	ac500000 */ 	sw	$s0,0x0($v0)
-/*    49a4c:	ac6a0000 */ 	sw	$t2,0x0($v1)
-.L00049a50:
-/*    49a50:	8d610000 */ 	lw	$at,0x0($t3)
-/*    49a54:	256b000c */ 	addiu	$t3,$t3,0xc
-/*    49a58:	254a000c */ 	addiu	$t2,$t2,0xc
-/*    49a5c:	ad41fff4 */ 	sw	$at,-0xc($t2)
-/*    49a60:	8d61fff8 */ 	lw	$at,-0x8($t3)
-/*    49a64:	ad41fff8 */ 	sw	$at,-0x8($t2)
-/*    49a68:	8d61fffc */ 	lw	$at,-0x4($t3)
-/*    49a6c:	156cfff8 */ 	bne	$t3,$t4,.L00049a50
-/*    49a70:	ad41fffc */ 	sw	$at,-0x4($t2)
-/*    49a74:	8fbf001c */ 	lw	$ra,0x1c($sp)
-/*    49a78:	8fb00018 */ 	lw	$s0,0x18($sp)
-/*    49a7c:	27bd0048 */ 	addiu	$sp,$sp,0x48
-/*    49a80:	03e00008 */ 	jr	$ra
-/*    49a84:	00000000 */ 	nop
-/*    49a88:	00000000 */ 	nop
-/*    49a8c:	00000000 */ 	nop
-);
+void __osViSwapContext()
+{
+	register OSViMode *vm;
+	register __OSViContext *vc;
+	u32 origin;
+	u32 hStart;
+	s32 vStart;
+	u32 nomValue;
+	u32 field;
+
+	field = 0;
+	vc = __osViNext;
+	vm = vc->modep;
+
+	field = IO_READ(VI_CURRENT_REG) & 1;
+
+	origin = osVirtualToPhysical(vc->framep) + (vm->fldRegs[field].origin);
+
+	if (vc->state & VI_STATE_XSCALE_UPDATED) {
+		vc->x.scale |= (vm->comRegs.xScale & ~VI_SCALE_MASK);
+	} else {
+		vc->x.scale = vm->comRegs.xScale;
+	}
+
+	if (vc->state & VI_STATE_YSCALE_UPDATED) {
+		nomValue = vm->fldRegs[field].yScale & VI_SCALE_MASK;
+		vc->y.scale = vc->y.factor * nomValue;
+		vc->y.scale |= vm->fldRegs[field].yScale & ~VI_SCALE_MASK;
+	} else {
+		vc->y.scale = vm->fldRegs[field].yScale;
+	}
+
+	vStart = var8005cefc + (vm->fldRegs[field].vStart - (var8005cefc << 16));
+	hStart = vm->comRegs.hStart;
+
+	if (vc->state & VI_STATE_BLACK) {
+		hStart = 0;
+	}
+
+	if (vc->state & VI_STATE_REPEATLINE) {
+		vc->y.scale = 0;
+		origin = osVirtualToPhysical(vc->framep);
+	}
+
+	if (vc->state & VI_STATE_FADE) {
+		vc->y.scale = (vc->y.offset << VI_SUBPIXEL_SH) & (VI_2_10_FPART_MASK << VI_SUBPIXEL_SH);
+		origin = osVirtualToPhysical(vc->framep);
+	}
+
+	IO_WRITE(VI_ORIGIN_REG, origin);
+	IO_WRITE(VI_WIDTH_REG, vm->comRegs.width);
+	IO_WRITE(VI_BURST_REG, vm->comRegs.burst);
+	IO_WRITE(VI_V_SYNC_REG, vm->comRegs.vSync);
+	IO_WRITE(VI_H_SYNC_REG, vm->comRegs.hSync);
+	IO_WRITE(VI_LEAP_REG, vm->comRegs.leap);
+	IO_WRITE(VI_H_START_REG, hStart);
+	IO_WRITE(VI_V_START_REG, vStart);
+	IO_WRITE(VI_V_BURST_REG, vm->fldRegs[field].vBurst);
+	IO_WRITE(VI_INTR_REG, vm->fldRegs[field].vIntr);
+	IO_WRITE(VI_X_SCALE_REG, vc->x.scale);
+	IO_WRITE(VI_Y_SCALE_REG, vc->y.scale);
+	IO_WRITE(VI_CONTROL_REG, vc->control);
+
+	__osViNext = __osViCurr;
+	__osViCurr = vc;
+	*__osViNext = *__osViCurr;
+}