diff --git a/Makefile b/Makefile
index 4dea321dd..7fb78eb56 100644
--- a/Makefile
+++ b/Makefile
@@ -7,12 +7,10 @@ QEMU_IRIX ?= tools/irix/qemu-irix
 IRIX_ROOT ?= tools/irix/root
 
 IDOCC ?= $(QEMU_IRIX) -silent -L $(IRIX_ROOT) $(IRIX_ROOT)/usr/bin/cc
-IDOAS ?= $(QEMU_IRIX) -silent -L $(IRIX_ROOT) $(IRIX_ROOT)/usr/bin/as
 
 ################################################################################
 
 QEMUCC = $(QEMU_IRIX) -silent -L $(IRIX_ROOT) $(IRIX_ROOT)/usr/bin/cc
-QEMUAS = $(QEMU_IRIX) -silent -L $(IRIX_ROOT) $(IRIX_ROOT)/usr/bin/as
 
 export ROMID
 
@@ -46,6 +44,11 @@ ifeq ($(ROMID),jpn-final)
 	VERSION=5
 endif
 
+DEFINES := VERSION=$(VERSION) NTSC=$(NTSC) PAL=$(PAL) JPN=$(JPN) PIRACYCHECKS=$(PIRACYCHECKS)
+
+C_DEFINES := $(foreach d,$(DEFINES),-D$(d))
+AS_DEFINES := $(foreach d,$(DEFINES),--defsym $(d)) --defsym _LANGUAGE_ASSEMBLY=1
+
 A_DIR := src/assets/$(ROMID)
 B_DIR := build/$(ROMID)
 E_DIR := extracted/$(ROMID)
@@ -62,6 +65,8 @@ else
     TOOLCHAIN := mips-elf
 endif
 
+AS := $(TOOLCHAIN)-as
+
 MIPSISET := -mips2 -32
 OPT_LVL := -O2
 LOOPUNROLL := -Wo,-loopunroll,0
@@ -153,11 +158,7 @@ ifeq ($(ROMID), ntsc-beta)
 $(B_DIR)/lib/ultra/io/pfsisplug.o: OPT_LVL := -O1
 endif
 
-CFLAGS = -DVERSION=$(VERSION) \
-	-DNTSC=$(NTSC) \
-	-DPAL=$(PAL) \
-	-DJPN=$(JPN) \
-	-DPIRACYCHECKS=$(PIRACYCHECKS) \
+CFLAGS = $(C_DEFINES) \
 	$(LOOPUNROLL) \
 	-Wab,-r4300_mul \
 	-non_shared \
@@ -171,6 +172,8 @@ CFLAGS = -DVERSION=$(VERSION) \
 	$(OPT_LVL) \
 	$(MIPSISET)
 
+ASFLAGS = -march=vr4300 -mabi=32 -Isrc/include $(AS_DEFINES)
+
 C_FILES := $(shell find src/lib src/game src/inflate -name '*.c')
 S_FILES := $(shell find src/lib src/game -name '*.s')
 
@@ -518,7 +521,7 @@ $(B_DIR)/%.o: src/%.c $(ASSETMGR_O_FILES)
 
 $(B_DIR)/%.o: src/%.s
 	@mkdir -p $(dir $@)
-	$(IDOAS) $(CFLAGS) $< -o $@
+	cpp -P -Wno-trigraphs -I src/include $(C_DEFINES) -D_LANGUAGE_ASSEMBLY -D_MIPSEB $< | $(AS) $(ASFLAGS) -o $@
 
 $(B_DIR)/assets/%.o: $(A_DIR)/%.c
 	@mkdir -p $(dir $@)
diff --git a/macros.inc b/src/include/macros.inc
similarity index 74%
rename from macros.inc
rename to src/include/macros.inc
index c97fd81f4..1adda2564 100644
--- a/macros.inc
+++ b/src/include/macros.inc
@@ -1,7 +1,4 @@
-# Assembly Macros
-
 .macro glabel label
     .global \label
     \label:
 .endm
-
diff --git a/src/lib/segments.s b/src/lib/segments.s
index 4429f1801..71363ce5d 100644
--- a/src/lib/segments.s
+++ b/src/lib/segments.s
@@ -1,41 +1,36 @@
-#include "asm_helper.h"
+#include "macros.inc"
 .set noat
 .set noreorder
 
-.text
-LEAF(segGetDataStart)
-	lui   v0, %hi(_dataSegmentStart)
-	jr    ra
-	addiu v0, v0, %lo(_dataSegmentStart)
-END(segGetDataStart)
+.section .text
 
-LEAF(segGetDatazipRomStart)
-	lui   v0, %hi(_datazipSegmentRomStart)
-	jr    ra
-	addiu v0, v0, %lo(_datazipSegmentRomStart)
-END(segGetDatazipRomStart)
+glabel segGetDataStart
+	lui   $v0, %hi(_dataSegmentStart)
+	jr    $ra
+	addiu $v0, $v0, %lo(_dataSegmentStart)
 
-LEAF(segGetInflateRomStart)
-	lui   v0, %hi(_inflateSegmentRomStart)
-	jr    ra
-	addiu v0, v0, %lo(_inflateSegmentRomStart)
-END(segGetInflateRomStart)
+glabel segGetDatazipRomStart
+	lui   $v0, %hi(_datazipSegmentRomStart)
+	jr    $ra
+	addiu $v0, $v0, %lo(_datazipSegmentRomStart)
 
-LEAF(segGetInflateRomStart2)
-	lui   v0, %hi(_inflateSegmentRomStart)
-	jr    ra
-	addiu v0, v0, %lo(_inflateSegmentRomStart)
-END(segGetInflateRomStart2)
+glabel segGetInflateRomStart
+	lui   $v0, %hi(_inflateSegmentRomStart)
+	jr    $ra
+	addiu $v0, $v0, %lo(_inflateSegmentRomStart)
 
-LEAF(segGetGamezipsRomStart)
-	lui   v0, %hi(_gamezipSegmentRomStart)
-	jr    ra
-	addiu v0, v0, %lo(_gamezipSegmentRomStart)
-END(segGetGamezipsRomStart)
+glabel segGetInflateRomStart2
+	lui   $v0, %hi(_inflateSegmentRomStart)
+	jr    $ra
+	addiu $v0, $v0, %lo(_inflateSegmentRomStart)
 
-LEAF(bootInflate)
-	lui   a3, %hi(inflate1173)
-	addiu a3, a3, %lo(inflate1173)
-	jr    a3
+glabel segGetGamezipsRomStart
+	lui   $v0, %hi(_gamezipSegmentRomStart)
+	jr    $ra
+	addiu $v0, $v0, %lo(_gamezipSegmentRomStart)
+
+glabel bootInflate
+	lui   $a3, %hi(inflate1173)
+	addiu $a3, $a3, %lo(inflate1173)
+	jr    $a3
 	nop
-END(bootInflate)
diff --git a/src/lib/ultra/gu/sqrtf.s b/src/lib/ultra/gu/sqrtf.s
index 458ecb434..c4772c204 100644
--- a/src/lib/ultra/gu/sqrtf.s
+++ b/src/lib/ultra/gu/sqrtf.s
@@ -1,7 +1,7 @@
-#include "asm_helper.h"
+#include "macros.inc"
 
-.text
-LEAF(sqrtf)
+.section .text
+
+glabel sqrtf
 	sqrt.s $f0, $f12
-	jr ra
-END(sqrtf)
+	jr $ra
diff --git a/src/lib/ultra/os/getcause.s b/src/lib/ultra/os/getcause.s
index 4ec0035f3..37cb87469 100644
--- a/src/lib/ultra/os/getcause.s
+++ b/src/lib/ultra/os/getcause.s
@@ -1,7 +1,8 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
-.text
-LEAF(__osGetCause)
-	STAY2(mfc0 v0, C0_CAUSE)
-	jr ra
-END(__osGetCause)
+.section .text
+
+glabel __osGetCause
+	STAY2(mfc0 $v0, C0_CAUSE)
+	jr $ra
diff --git a/src/lib/ultra/os/getcount.s b/src/lib/ultra/os/getcount.s
index 1158334fb..95986949d 100644
--- a/src/lib/ultra/os/getcount.s
+++ b/src/lib/ultra/os/getcount.s
@@ -1,7 +1,8 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
-.text
-LEAF(osGetCount)
-	STAY2(mfc0 v0, C0_COUNT)
-	jr ra
-END(osGetCount)
+.section .text
+
+glabel osGetCount
+	STAY2(mfc0 $v0, C0_COUNT)
+	jr $ra
diff --git a/src/lib/ultra/os/getfpccsr.s b/src/lib/ultra/os/getfpccsr.s
index 7fd81e912..2803a8927 100644
--- a/src/lib/ultra/os/getfpccsr.s
+++ b/src/lib/ultra/os/getfpccsr.s
@@ -1,7 +1,8 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
-.text
-LEAF(__osGetFpcCsr)
-	STAY2(cfc1 v0, $31)
-	jr ra
-END(__osGetFpcCsr)
+.section .text
+
+glabel __osGetFpcCsr
+	STAY2(cfc1 $v0, $31)
+	jr $ra
diff --git a/src/lib/ultra/os/getsr.s b/src/lib/ultra/os/getsr.s
index 4f3fa41b5..e7f723cd9 100644
--- a/src/lib/ultra/os/getsr.s
+++ b/src/lib/ultra/os/getsr.s
@@ -1,7 +1,8 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
-.text
-LEAF(__osGetSR)
-	STAY2(mfc0 v0, C0_SR)
-	jr ra
-END(__osGetSR)
+.section .text
+
+glabel __osGetSR
+	STAY2(mfc0 $v0, C0_SR)
+	jr $ra
diff --git a/src/lib/ultra/os/maptlbrdb.s b/src/lib/ultra/os/maptlbrdb.s
index 3ee064196..16dca990d 100644
--- a/src/lib/ultra/os/maptlbrdb.s
+++ b/src/lib/ultra/os/maptlbrdb.s
@@ -1,29 +1,30 @@
 #include "asm_helper.h"
+#include "macros.inc"
 .set noat
 .set noreorder
 
-.text
-LEAF(osMapTLBRdb)
-	mfc0  t0, C0_ENTRYHI
-	li    t1, 1
-	mtc0  t1, C0_INX
-	mtc0  zero, C0_PAGEMASK
-	li    t2, TLBLO_UNCACHED | TLBLO_D | TLBLO_V | TLBLO_G
-	li    t1, K2BASE
-	mtc0  t1, C0_ENTRYHI
-	li    t1, KUSIZE
-	srl   t3, t1,TLBLO_PFNSHIFT
-	or    t3, t3,t2
-	mtc0  t3, C0_ENTRYLO0
-	li    t1, TLBLO_G
-	mtc0  t1, C0_ENTRYLO1
+.section .text
+
+glabel osMapTLBRdb
+	mfc0  $t0, C0_ENTRYHI
+	li    $t1, 1
+	mtc0  $t1, C0_INX
+	mtc0  $zero, C0_PAGEMASK
+	li    $t2, TLBLO_UNCACHED | TLBLO_D | TLBLO_V | TLBLO_G
+	li    $t1, K2BASE
+	mtc0  $t1, C0_ENTRYHI
+	li    $t1, KUSIZE
+	srl   $t3, $t1, TLBLO_PFNSHIFT
+	or    $t3, $t3, $t2
+	mtc0  $t3, C0_ENTRYLO0
+	li    $t1, TLBLO_G
+	mtc0  $t1, C0_ENTRYLO1
 	nop
 	tlbwi
 	nop
 	nop
 	nop
 	nop
-	mtc0  t0, C0_ENTRYHI
-	jr    ra
+	mtc0  $t0, C0_ENTRYHI
+	jr    $ra
 	nop
-END(osMapTLBRdb)
diff --git a/src/lib/ultra/os/setcompare.s b/src/lib/ultra/os/setcompare.s
index 5408cd044..da08c3609 100644
--- a/src/lib/ultra/os/setcompare.s
+++ b/src/lib/ultra/os/setcompare.s
@@ -1,9 +1,10 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
 .set noreorder
-.text
-LEAF(__osSetCompare)
-	mtc0 a0, C0_COMPARE
-	jr ra
+.section .text
+
+glabel __osSetCompare
+	mtc0 $a0, C0_COMPARE
+	jr   $ra
 	nop
-END(__osSetCompare)
diff --git a/src/lib/ultra/os/setfpccsr.s b/src/lib/ultra/os/setfpccsr.s
index 8d02b9c8f..e8c68db8f 100644
--- a/src/lib/ultra/os/setfpccsr.s
+++ b/src/lib/ultra/os/setfpccsr.s
@@ -1,11 +1,10 @@
-#include "asm_helper.h"
+#include "macros.inc"
 
 .set noreorder
 .text
 
-LEAF(__osSetFpcCsr)
-	cfc1 v0, $31
-	ctc1 a0, $31
-	jr ra
+glabel __osSetFpcCsr
+	cfc1 $v0, $31
+	ctc1 $a0, $31
+	jr   $ra
 	nop
-END(__osSetFpcCsr)
diff --git a/src/lib/ultra/os/setintmask.c b/src/lib/ultra/os/setintmask.c
deleted file mode 100644
index 5373b76d0..000000000
--- a/src/lib/ultra/os/setintmask.c
+++ /dev/null
@@ -1,80 +0,0 @@
-#include <libultra_internal.h>
-#include "data.h"
-
-const u32 var70059e30[] = {0x05550556};
-const u32 var70059e34[] = {0x0559055a};
-const u32 var70059e38[] = {0x05650566};
-const u32 var70059e3c[] = {0x0569056a};
-const u32 var70059e40[] = {0x05950596};
-const u32 var70059e44[] = {0x0599059a};
-const u32 var70059e48[] = {0x05a505a6};
-const u32 var70059e4c[] = {0x05a905aa};
-const u32 var70059e50[] = {0x06550656};
-const u32 var70059e54[] = {0x0659065a};
-const u32 var70059e58[] = {0x06650666};
-const u32 var70059e5c[] = {0x0669066a};
-const u32 var70059e60[] = {0x06950696};
-const u32 var70059e64[] = {0x0699069a};
-const u32 var70059e68[] = {0x06a506a6};
-const u32 var70059e6c[] = {0x06a906aa};
-const u32 var70059e70[] = {0x09550956};
-const u32 var70059e74[] = {0x0959095a};
-const u32 var70059e78[] = {0x09650966};
-const u32 var70059e7c[] = {0x0969096a};
-const u32 var70059e80[] = {0x09950996};
-const u32 var70059e84[] = {0x0999099a};
-const u32 var70059e88[] = {0x09a509a6};
-const u32 var70059e8c[] = {0x09a909aa};
-const u32 var70059e90[] = {0x0a550a56};
-const u32 var70059e94[] = {0x0a590a5a};
-const u32 var70059e98[] = {0x0a650a66};
-const u32 var70059e9c[] = {0x0a690a6a};
-const u32 var70059ea0[] = {0x0a950a96};
-const u32 var70059ea4[] = {0x0a990a9a};
-const u32 var70059ea8[] = {0x0aa50aa6};
-const u32 var70059eac[] = {0x0aa90aaa};
-
-GLOBAL_ASM(
-glabel osSetIntMask
-/*    48650:	400c6000 */ 	mfc0	$t4,$12
-/*    48654:	3182ff01 */ 	andi	$v0,$t4,0xff01
-/*    48658:	3c088006 */ 	lui	$t0,%hi(__osGlobalIntMask)
-/*    4865c:	2508cf70 */ 	addiu	$t0,$t0,%lo(__osGlobalIntMask)
-/*    48660:	8d0b0000 */ 	lw	$t3,0x0($t0)
-/*    48664:	2401ffff */ 	addiu	$at,$zero,-1
-/*    48668:	01614026 */ 	xor	$t0,$t3,$at
-/*    4866c:	3108ff00 */ 	andi	$t0,$t0,0xff00
-/*    48670:	00481025 */ 	or	$v0,$v0,$t0
-/*    48674:	3c0aa430 */ 	lui	$t2,0xa430
-/*    48678:	8d4a000c */ 	lw	$t2,0xc($t2)
-/*    4867c:	11400005 */ 	beqz	$t2,.L00048694
-/*    48680:	000b4c02 */ 	srl	$t1,$t3,0x10
-/*    48684:	2401ffff */ 	addiu	$at,$zero,-1
-/*    48688:	01214826 */ 	xor	$t1,$t1,$at
-/*    4868c:	3129003f */ 	andi	$t1,$t1,0x3f
-/*    48690:	01495025 */ 	or	$t2,$t2,$t1
-.L00048694:
-/*    48694:	000a5400 */ 	sll	$t2,$t2,0x10
-/*    48698:	004a1025 */ 	or	$v0,$v0,$t2
-/*    4869c:	3c01003f */ 	lui	$at,0x3f
-/*    486a0:	00814024 */ 	and	$t0,$a0,$at
-/*    486a4:	010b4024 */ 	and	$t0,$t0,$t3
-/*    486a8:	000843c2 */ 	srl	$t0,$t0,0xf
-/*    486ac:	3c0a7006 */ 	lui	$t2,%hi(var70059e30)
-/*    486b0:	01485021 */ 	addu	$t2,$t2,$t0
-/*    486b4:	954a9e30 */ 	lhu	$t2,%lo(var70059e30)($t2)
-/*    486b8:	3c01a430 */ 	lui	$at,0xa430
-/*    486bc:	ac2a000c */ 	sw	$t2,0xc($at)
-/*    486c0:	3088ff01 */ 	andi	$t0,$a0,0xff01
-/*    486c4:	3169ff00 */ 	andi	$t1,$t3,0xff00
-/*    486c8:	01094024 */ 	and	$t0,$t0,$t1
-/*    486cc:	3c01ffff */ 	lui	$at,0xffff
-/*    486d0:	342100ff */ 	ori	$at,$at,0xff
-/*    486d4:	01816024 */ 	and	$t4,$t4,$at
-/*    486d8:	01886025 */ 	or	$t4,$t4,$t0
-/*    486dc:	408c6000 */ 	mtc0	$t4,$12
-/*    486e0:	00000000 */ 	nop
-/*    486e4:	00000000 */ 	nop
-/*    486e8:	03e00008 */ 	jr	$ra
-/*    486ec:	00000000 */ 	nop
-);
diff --git a/src/lib/ultra/os/setintmask.s b/src/lib/ultra/os/setintmask.s
new file mode 100644
index 000000000..73c50e25e
--- /dev/null
+++ b/src/lib/ultra/os/setintmask.s
@@ -0,0 +1,117 @@
+#include "macros.inc"
+.set noat
+.set noreorder
+
+.section .text
+
+glabel osSetIntMask
+	mfc0  $t4, $12
+	andi  $v0, $t4, 0xff01
+	lui   $t0, %hi(__osGlobalIntMask)
+	addiu $t0, $t0, %lo(__osGlobalIntMask)
+	lw    $t3, 0x0($t0)
+	addiu $at, $zero, -1
+	xor   $t0, $t3, $at
+	andi  $t0, $t0, 0xff00
+	or    $v0, $v0, $t0
+	lui   $t2, 0xa430
+	lw    $t2, 0xc($t2)
+	beqz  $t2, .L00048694
+	srl   $t1, $t3, 0x10
+	addiu $at, $zero, -1
+	xor   $t1, $t1, $at
+	andi  $t1, $t1, 0x3f
+	or    $t2, $t2, $t1
+.L00048694:
+	sll   $t2, $t2, 0x10
+	or    $v0, $v0, $t2
+	lui   $at, 0x3f
+	and   $t0, $a0, $at
+	and   $t0, $t0, $t3
+	srl   $t0, $t0, 0xf
+	lui   $t2, %hi(var70059e30)
+	addu  $t2, $t2, $t0
+	lhu   $t2, %lo(var70059e30)($t2)
+	lui   $at, 0xa430
+	sw    $t2, 0xc($at)
+	andi  $t0, $a0, 0xff01
+	andi  $t1, $t3, 0xff00
+	and   $t0, $t0, $t1
+	lui   $at, 0xffff
+	ori   $at, $at, 0xff
+	and   $t4, $t4, $at
+	or    $t4, $t4, $t0
+	mtc0  $t4, $12
+ 	nop
+ 	nop
+	jr    $ra
+ 	nop
+
+.section .rodata
+
+glabel var70059e30
+.half 0x0555
+.half 0x0556
+.half 0x0559
+.half 0x055a
+.half 0x0565
+.half 0x0566
+.half 0x0569
+.half 0x056a
+.half 0x0595
+.half 0x0596
+.half 0x0599
+.half 0x059a
+.half 0x05a5
+.half 0x05a6
+.half 0x05a9
+.half 0x05aa
+.half 0x0655
+.half 0x0656
+.half 0x0659
+.half 0x065a
+.half 0x0665
+.half 0x0666
+.half 0x0669
+.half 0x066a
+.half 0x0695
+.half 0x0696
+.half 0x0699
+.half 0x069a
+.half 0x06a5
+.half 0x06a6
+.half 0x06a9
+.half 0x06aa
+.half 0x0955
+.half 0x0956
+.half 0x0959
+.half 0x095a
+.half 0x0965
+.half 0x0966
+.half 0x0969
+.half 0x096a
+.half 0x0995
+.half 0x0996
+.half 0x0999
+.half 0x099a
+.half 0x09a5
+.half 0x09a6
+.half 0x09a9
+.half 0x09aa
+.half 0x0a55
+.half 0x0a56
+.half 0x0a59
+.half 0x0a5a
+.half 0x0a65
+.half 0x0a66
+.half 0x0a69
+.half 0x0a6a
+.half 0x0a95
+.half 0x0a96
+.half 0x0a99
+.half 0x0a9a
+.half 0x0aa5
+.half 0x0aa6
+.half 0x0aa9
+.half 0x0aaa
+
diff --git a/src/lib/ultra/os/setsr.s b/src/lib/ultra/os/setsr.s
index 63cc3d73b..6453176e5 100644
--- a/src/lib/ultra/os/setsr.s
+++ b/src/lib/ultra/os/setsr.s
@@ -1,10 +1,11 @@
 #include "asm_helper.h"
+#include "macros.inc"
 
 .set noreorder
-.text
-LEAF(__osSetSR)
-	mtc0 a0, C0_SR
+.section .text
+
+glabel __osSetSR
+	mtc0 $a0, C0_SR
 	nop
-	jr ra
+	jr   $ra
 	nop
-END(__osSetSR)
diff --git a/tools/asmpreproc/prelude.s b/tools/asmpreproc/prelude.s
index 0c111a2a9..6450b7f6b 100644
--- a/tools/asmpreproc/prelude.s
+++ b/tools/asmpreproc/prelude.s
@@ -1,5 +1,5 @@
 .set noat
 .set noreorder
 .set gp=64
-.include "macros.inc"
+.include "src/include/macros.inc"