From 12bb254668d2084720be4645d683428f2a917e49 Mon Sep 17 00:00:00 2001
From: Thar0 <17233964+Thar0@users.noreply.github.com>
Date: Fri, 14 Jun 2024 22:22:10 +0100
Subject: [PATCH 1/5] Support building for multiple MIPS ABIs: o32 (default),
 n32 and eabi32

---
 Makefile                            |  49 ++++---
 include/ultra64/asm.h               |   9 +-
 include/ultra64/regdef.h            | 203 +++++++++++++++++++++++++---
 include/ultra64/thread.h            |  42 ++++++
 include/ultra64/xstdio.h            |   3 +-
 src/gcc_fix/missing_gcc_functions.c |  19 +++
 src/libultra/mgu/scale.s            |  19 ++-
 src/libultra/mgu/translate.s        |  18 +++
 src/libultra/os/createthread.c      |   4 +
 src/libultra/os/exceptasm.s         |  59 +++++++-
 src/libultra/os/initialize.c        |   7 +
 11 files changed, 385 insertions(+), 47 deletions(-)

diff --git a/Makefile b/Makefile
index 3a7e3a7004..2d1f558307 100644
--- a/Makefile
+++ b/Makefile
@@ -6,11 +6,6 @@ SHELL = /usr/bin/env bash
 
 #### Build options ####
 
-# Build options can be changed by modifying them below, or by appending 'SETTING=value' to all 'make' commands
-# (e.g. 'make setup VERSION=ntsc-1.0' and 'make VERSION=ntsc-1.0' to build the NTSC 1.0 version).
-# Alternatively, you can create a file called .make_options.mk (gitignored by default) and add 'SETTING=value'
-# there to avoid modifying the Makefile directly.
-
 -include .make_options.mk
 
 COMPILER ?= gcc
@@ -49,6 +44,8 @@ REGION ?= US
 # This means the debug test scenes and some debug graphics in the elf_msg actors will not work as expected.
 # This may also be used to disable debug features on debug ROMs by setting DEBUG_FEATURES to 0
 DEBUG_FEATURES ?= 1
+# MIPS ABI, can be one of "32", "n32" or "eabi"
+ABI := 32
 
 # Version-specific settings
 REGIONAL_CHECKSUM := 0
@@ -266,12 +263,12 @@ EGCS_PREFIX := tools/egcs/$(DETECTED_OS)/
 EGCS_CC := $(EGCS_PREFIX)gcc -B $(EGCS_PREFIX)
 EGCS_CCAS := $(EGCS_CC) -x assembler-with-cpp
 
-AS      := $(MIPS_BINUTILS_PREFIX)as
-LD      := $(MIPS_BINUTILS_PREFIX)ld
-OBJCOPY := $(MIPS_BINUTILS_PREFIX)objcopy
-OBJDUMP := $(MIPS_BINUTILS_PREFIX)objdump
-NM      := $(MIPS_BINUTILS_PREFIX)nm
-STRIP   := $(MIPS_BINUTILS_PREFIX)strip
+AS       := $(MIPS_BINUTILS_PREFIX)as
+LD       := $(MIPS_BINUTILS_PREFIX)ld
+OBJCOPY  := $(MIPS_BINUTILS_PREFIX)objcopy
+OBJDUMP  := $(MIPS_BINUTILS_PREFIX)objdump
+NM       := $(MIPS_BINUTILS_PREFIX)nm
+STRIP    := $(MIPS_BINUTILS_PREFIX)strip
 
 # Command prefix to preprocess a file before running the compiler
 PREPROCESS :=
@@ -342,12 +339,24 @@ ifeq ($(DEBUG_FEATURES),1)
   GBI_DEFINES += -DGBI_DEBUG
 endif
 
+ABI_FLAGS :=
+
+# Select ld output format based on toolchain default and any additional ABI-specific flags
+ifeq ($(ABI),n32)
+  LD_OUTPUT_FORMAT := $(shell $(LD) --print-output-format | sed -E 's/elf(32|64)-(n)?(trad)?(big|little)mips/elf\1-n\3\4mips/')
+else
+  ifeq ($(ABI),eabi)
+    ABI_FLAGS += -mgp32 -mfp32
+  endif
+  LD_OUTPUT_FORMAT := $(shell $(LD) --print-output-format | sed -E 's/elf(32|64)-(n)?(trad)?(big|little)mips/elf\1-\3\4mips/')
+endif
+ 
 CPPFLAGS += -P -xc -fno-dollars-in-identifiers $(CPP_DEFINES)
-ASFLAGS += -march=vr4300 -32 -no-pad-sections -Iinclude -I$(EXTRACTED_DIR)
+ASFLAGS += -march=vr4300 -mabi=$(ABI) $(ABI_FLAGS) -no-pad-sections -Iinclude -I$(EXTRACTED_DIR)
 
 ifeq ($(COMPILER),gcc)
-  CFLAGS += $(CPP_DEFINES) $(GBI_DEFINES) -G 0 -nostdinc -MD -MP $(INC) -march=vr4300 -mfix4300 -mabi=32 -mno-abicalls -mdivide-breaks -fno-PIC -fno-common -ffreestanding -funsigned-char -fbuiltin -fno-builtin-sinf -fno-builtin-cosf $(CHECK_WARNINGS)
-  CCASFLAGS += $(CPP_DEFINES) $(GBI_DEFINES) -G 0 -nostdinc -MD -MP $(INC) -march=vr4300 -mfix4300 -mabi=32 -mno-abicalls -fno-PIC -fno-common -Wa,-no-pad-sections
+  CFLAGS += $(CPP_DEFINES) $(GBI_DEFINES) -G 0 -nostdinc -MD -MP $(INC) -march=vr4300 -mfix4300 -mabi=$(ABI) $(ABI_FLAGS) -mno-abicalls -mdivide-breaks -fno-PIC -fno-common -ffreestanding -funsigned-char -fbuiltin -fno-builtin-sinf -fno-builtin-cosf $(CHECK_WARNINGS)
+  CCASFLAGS += $(CPP_DEFINES) $(GBI_DEFINES) -G 0 -nostdinc -MD -MP $(INC) -march=vr4300 -mfix4300 -mabi=$(ABI) $(ABI_FLAGS) -mno-abicalls -fno-PIC -fno-common -Wa,-no-pad-sections
   MIPS_VERSION := -mips3
   CC_CHECK = @:
 endif
@@ -631,6 +640,8 @@ $(ROM): $(ELF)
 	$(V)$(ELF2ROM) -cic $(CIC) $< $@
 	@$(PRINT) "==== Build Options ====$(NO_COL)\n"
 	@$(PRINT) "${GREEN}OoT Version: $(BLUE)$(VERSION)$(NO_COL)\n"
+	@$(PRINT) "${GREEN}MIPS Toolchain: $(BLUE)$(MIPS_BINUTILS_PREFIX)$(NO_COL)\n"
+	@$(PRINT) "${GREEN}MIPS ABI: $(BLUE)$(ABI)$(NO_COL)\n"
 	@$(PRINT) "${GREEN}Code Version: $(BLUE)$(PACKAGE_VERSION)$(NO_COL)\n"
 	@$(PRINT) "${GREEN}Debug Build: $(BLUE)$(DEBUG_FEATURES)$(NO_COL)\n"
 	@$(PRINT) "${GREEN}Opt. Flags: $(BLUE)$(OPTFLAGS)$(NO_COL)\n"
@@ -652,7 +663,7 @@ endif
 
 COM_PLUGIN := tools/com-plugin/common-plugin.so
 
-LDFLAGS := -T $(LDSCRIPT) -T $(BUILD_DIR)/linker_scripts/makerom.ld -T $(BUILD_DIR)/undefined_syms.txt --no-check-sections --accept-unknown-input-arch --emit-relocs -Map $(MAP)
+LDFLAGS := --oformat $(LD_OUTPUT_FORMAT) -T $(LDSCRIPT) -T $(BUILD_DIR)/linker_scripts/makerom.ld -T $(BUILD_DIR)/undefined_syms.txt --no-check-sections --accept-unknown-input-arch --emit-relocs -Map $(MAP)
 ifeq ($(PLATFORM),IQUE)
   ifeq ($(NON_MATCHING),0)
     LDFLAGS += -plugin $(COM_PLUGIN) -plugin-opt order=$(BASEROM_DIR)/bss-order.txt
@@ -765,7 +776,7 @@ $(BUILD_DIR)/src/%.o: src/%.s
 
 # Incremental link to move z_message and z_game_over data into rodata
 $(BUILD_DIR)/src/code/z_message_z_game_over.o: $(BUILD_DIR)/src/code/z_message.o $(BUILD_DIR)/src/code/z_game_over.o
-	$(V)$(LD) -r -G 0 -T linker_scripts/data_with_rodata.ld -o $@ $^
+	$(V)$(LD) -r -G 0 --oformat $(LD_OUTPUT_FORMAT) -T linker_scripts/data_with_rodata.ld -o $@ $^
 	$(V)$(PYTHON) tools/patch_data_with_rodata_mdebug.py $@
 
 DEP_FILES += $(BUILD_DIR)/src/code/z_message.d $(BUILD_DIR)/src/code/z_game_over.d
@@ -788,7 +799,7 @@ $(BUILD_DIR)/src/audio/game/session_init.o: src/audio/game/session_init.c $(BUIL
 	$(call print_two_args,Compiling:,$<,$@)
 	$(V)$(CC_CHECK) $< -o $@
 	$(V)$(CC) -c $(CFLAGS) $(MIPS_VERSION) $(OPTFLAGS) -o $(@:.o=.tmp) $<
-	$(V)$(LD) -r -T linker_scripts/data_with_rodata.ld -o $@ $(@:.o=.tmp)
+	$(V)$(LD) -r --oformat $(LD_OUTPUT_FORMAT) -T linker_scripts/data_with_rodata.ld -o $@ $(@:.o=.tmp)
 	$(V)$(PYTHON) tools/patch_data_with_rodata_mdebug.py $@
 	$(V)$(OBJDUMP_CMD)
 
@@ -906,7 +917,7 @@ $(BUILD_DIR)/assets/audio/soundfonts/%.o: $(BUILD_DIR)/assets/audio/soundfonts/%
 # compile c to unlinked object
 	$(V)$(CC) -c $(CFLAGS) $(MIPS_VERSION) $(OPTFLAGS) -I include/audio -o $(@:.o=.tmp) $<
 # partial link
-	$(V)$(LD) -r -T linker_scripts/soundfont.ld $(@:.o=.tmp) -o $(@:.o=.tmp2)
+	$(V)$(LD) -r --oformat $(LD_OUTPUT_FORMAT) -T linker_scripts/soundfont.ld $(@:.o=.tmp) -o $(@:.o=.tmp2)
 # patch defined symbols to be ABS symbols so that they remain file-relative offsets forever
 	$(V)$(SFPATCH) $(@:.o=.tmp2) $(@:.o=.tmp2)
 # write start and size symbols afterwards, filename != symbolic name so source symbolic name from the .name file written by sfc
@@ -963,7 +974,7 @@ $(BUILD_DIR)/src/audio/tables/sequence_table.o: CFLAGS += -I include/tables
 $(BUILD_DIR)/src/audio/tables/%.o: src/audio/tables/%.c
 	$(V)$(CC_CHECK) $< -o $@
 	$(V)$(CC) -c $(CFLAGS) $(MIPS_VERSION) $(OPTFLAGS) -o $(@:.o=.tmp) $<
-	$(V)$(LD) -r -T linker_scripts/data_with_rodata.ld $(@:.o=.tmp) -o $@
+	$(V)$(LD) -r --oformat $(LD_OUTPUT_FORMAT) -T linker_scripts/data_with_rodata.ld $(@:.o=.tmp) -o $@
 	$(V)$(PYTHON) tools/patch_data_with_rodata_mdebug.py $@
 	@$(RM) $(@:.o=.tmp)
 
diff --git a/include/ultra64/asm.h b/include/ultra64/asm.h
index d887673fa6..82165db394 100644
--- a/include/ultra64/asm.h
+++ b/include/ultra64/asm.h
@@ -108,12 +108,19 @@
     .set x, y
 #endif
 
+#if !defined(_MIPS_SIM) || _MIPS_SIM != _ABIO32
+.set $t4, $ta0
+.set $t5, $ta1
+.set $t6, $ta2
+.set $t7, $ta3
+#endif
+
 #endif
 
 /**
  *  Stack Alignment
  */
-#if   (_MIPS_SIM == _ABIO32)
+#if defined(_MIPS_SIM) && (_MIPS_SIM == _ABIO32)
 #define NARGSAVE 4      /* space for 4 args must be allocated */
 #define ALSZ    (8-1)
 #define ALMASK ~(8-1)
diff --git a/include/ultra64/regdef.h b/include/ultra64/regdef.h
index a3b2832180..127846182d 100644
--- a/include/ultra64/regdef.h
+++ b/include/ultra64/regdef.h
@@ -7,7 +7,8 @@
 #define _MIPS_SIM_ABI64 _ABI64
 #endif
 
-#if (_MIPS_SIM == _MIPS_SIM_ABI32)
+#if !defined(_MIPS_SIM) /* EABI32 */
+
 #define zero    $0
 #define AT      $at
 #define v0      $2
@@ -17,9 +18,13 @@
 #define a2      $6
 #define a3      $7
 #define t0      $8
+#define a4      $8
 #define t1      $9
+#define a5      $9
 #define t2      $10
+#define a6      $10
 #define t3      $11
+#define a7      $11
 #define t4      $12
 #define ta0     $12
 #define t5      $13
@@ -41,14 +46,49 @@
 #define jp      $25
 #define k0      $26
 #define k1      $27
-#define gp      $28
+#define GP      $28
 #define sp      $29
 #define fp      $30
 #define s8      $30
 #define ra      $31
-#endif
 
-#if (_MIPS_SIM == _MIPS_SIM_ABI64)
+#define fv0     $f0
+#define fv0f    $f1
+#define fv1     $f2
+#define fv1f    $f3
+#define ft0     $f4
+#define ft0f    $f5
+#define ft1     $f6
+#define ft1f    $f7
+#define ft2     $f8
+#define ft2f    $f9
+#define ft3     $f10
+#define ft3f    $f11
+#define fa0     $f12
+#define fa0f    $f13
+#define fa1     $f14
+#define fa1f    $f15
+#define fa2     $f16
+#define fa2f    $f17
+#define fa3     $f18
+#define fa3f    $f19
+#define fs0     $f20
+#define fs0f    $f21
+#define fs1     $f22
+#define fs1f    $f23
+#define fs2     $f24
+#define fs2f    $f25
+#define fs3     $f26
+#define fs3f    $f27
+#define fs4     $f28
+#define fs4f    $f29
+#define fs5     $f30
+#define fs5f    $f31
+
+#else
+
+#if (_MIPS_SIM == _MIPS_SIM_ABI32) /* O32 */
+
 #define zero    $0
 #define AT      $at
 #define v0      $2
@@ -57,18 +97,18 @@
 #define a1      $5
 #define a2      $6
 #define a3      $7
-#define a4      $8
-#define ta0     $8
-#define a5      $9
-#define ta1     $9
-#define a6      $10
-#define ta2     $10
-#define a7      $11
-#define ta3     $11
-#define t0      $12
-#define t1      $13
-#define t2      $14
-#define t3      $15
+#define t0      $8
+#define t1      $9
+#define t2      $10
+#define t3      $11
+#define t4      $12
+#define ta0     $12
+#define t5      $13
+#define ta1     $13
+#define t6      $14
+#define ta2     $14
+#define t7      $15
+#define ta3     $15
 #define s0      $16
 #define s1      $17
 #define s2      $18
@@ -82,14 +122,12 @@
 #define jp      $25
 #define k0      $26
 #define k1      $27
-#define gp      $28
+#define GP      $28
 #define sp      $29
 #define fp      $30
 #define s8      $30
 #define ra      $31
-#endif
 
-#if (_MIPS_SIM == _MIPS_SIM_ABI32)
 #define fv0     $f0
 #define fv0f    $f1
 #define fv1     $f2
@@ -122,9 +160,131 @@
 #define fs4f    $f29
 #define fs5     $f30
 #define fs5f    $f31
+
 #endif
 
-#if (_MIPS_SIM == _MIPS_SIM_ABI64)
+#if (_MIPS_SIM == _MIPS_SIM_NABI32) /* N32 */
+
+#define zero    $0
+#define AT      $1
+#define v0      $2
+#define v1      $3
+#define a0      $4
+#define a1      $5
+#define a2      $6
+#define a3      $7
+#define a4      $8
+#define t0      $8
+#define ta0     $8
+#define a5      $9
+#define t1      $9
+#define ta1     $9
+#define a6      $10
+#define t2      $10
+#define ta2     $10
+#define a7      $11
+#define t3      $11
+#define ta3     $11
+#define t4      $12
+#define t5      $13
+#define t6      $14
+#define t7      $15
+#define s0      $16
+#define s1      $17
+#define s2      $18
+#define s3      $19
+#define s4      $20
+#define s5      $21
+#define s6      $22
+#define s7      $23
+#define t8      $24
+#define t9      $25
+#define k0      $26
+#define kt0     $26
+#define k1      $27
+#define kt1     $27
+#define GP      $28
+#define sp      $29
+#define s8      $30
+#define fp      $30
+#define ra      $31
+
+#define fv0     $f0
+#define ft14    $f1
+#define fv1     $f2
+#define ft15    $f3
+#define ft0     $f4
+#define ft1     $f5
+#define ft2     $f6
+#define ft3     $f7
+#define ft4     $f8
+#define ft5     $f9
+#define ft6     $f10
+#define ft7     $f11
+#define fa0     $f12
+#define fa1     $f13
+#define fa2     $f14
+#define fa3     $f15
+#define fa4     $f16
+#define fa5     $f17
+#define fa6     $f18
+#define fa7     $f19
+#define fs0     $f20
+#define ft8     $f21
+#define fs1     $f22
+#define ft9     $f23
+#define fs2     $f24
+#define ft10    $f25
+#define fs3     $f26
+#define ft11    $f27
+#define fs4     $f28
+#define ft12    $f29
+#define fs5     $f30
+#define ft13    $f31
+
+#endif
+
+#if (_MIPS_SIM == _MIPS_SIM_ABI64) /* O64 */
+
+#define zero    $0
+#define AT      $at
+#define v0      $2
+#define v1      $3
+#define a0      $4
+#define a1      $5
+#define a2      $6
+#define a3      $7
+#define a4      $8
+#define ta0     $8
+#define a5      $9
+#define ta1     $9
+#define a6      $10
+#define ta2     $10
+#define a7      $11
+#define ta3     $11
+#define t0      $12
+#define t1      $13
+#define t2      $14
+#define t3      $15
+#define s0      $16
+#define s1      $17
+#define s2      $18
+#define s3      $19
+#define s4      $20
+#define s5      $21
+#define s6      $22
+#define s7      $23
+#define t8      $24
+#define t9      $25
+#define jp      $25
+#define k0      $26
+#define k1      $27
+#define GP      $28
+#define sp      $29
+#define fp      $30
+#define s8      $30
+#define ra      $31
+
 #define fv0     $f0
 #define fv1     $f2
 #define fa0     $f12
@@ -157,6 +317,9 @@
 #define fs5     $f29
 #define fs6     $f30
 #define fs7     $f31
+
+#endif
+
 #endif
 
 #define fcr31   $31
diff --git a/include/ultra64/thread.h b/include/ultra64/thread.h
index 3c2733f150..6737261f02 100644
--- a/include/ultra64/thread.h
+++ b/include/ultra64/thread.h
@@ -43,8 +43,15 @@ typedef struct __OSThreadContext {
     /* 0x0E8 */ u64 lo, hi;
     /* 0x0F8 */ u32 sr, pc, cause, badvaddr, rcp;
     /* 0x10C */ u32 fpcsr;
+#if !defined(_MIPS_SIM) || _MIPS_SIM != _ABIN32
     /* 0x110 */ __OSfp  fp0,  fp2,  fp4,  fp6,  fp8, fp10, fp12, fp14;
     /* 0x150 */ __OSfp fp16, fp18, fp20, fp22, fp24, fp26, fp28, fp30;
+#else
+                __OSfp  fp0,  fp1,  fp2,  fp3,  fp4,  fp5,  fp6,  fp7;
+                __OSfp  fp8,  fp9, fp10, fp11, fp12, fp13, fp14, fp15;
+                __OSfp fp16, fp17, fp18, fp19, fp20, fp21, fp22, fp23;
+                __OSfp fp24, fp25, fp26, fp27, fp28, fp29, fp30, fp31;
+#endif
 } __OSThreadContext; // size = 0x190
 
 typedef struct __OSThreadprofile {
@@ -122,6 +129,7 @@ typedef struct __OSThreadTail {
 #define THREAD_BADVADDR (THREAD_CONTEXT + 0x104)
 #define THREAD_RCP      (THREAD_CONTEXT + 0x108)
 #define THREAD_FPCSR    (THREAD_CONTEXT + 0x10C)
+#if !defined(_MIPS_SIM) || _MIPS_SIM != _ABIN32
 #define THREAD_FP0      (THREAD_CONTEXT + 0x110)
 #define THREAD_FP2      (THREAD_CONTEXT + 0x118)
 #define THREAD_FP4      (THREAD_CONTEXT + 0x120)
@@ -138,6 +146,40 @@ typedef struct __OSThreadTail {
 #define THREAD_FP26     (THREAD_CONTEXT + 0x178)
 #define THREAD_FP28     (THREAD_CONTEXT + 0x180)
 #define THREAD_FP30     (THREAD_CONTEXT + 0x188)
+#else
+#define THREAD_FP0      (THREAD_CONTEXT + 0x110)
+#define THREAD_FP1      (THREAD_CONTEXT + 0x118)
+#define THREAD_FP2      (THREAD_CONTEXT + 0x120)
+#define THREAD_FP3      (THREAD_CONTEXT + 0x128)
+#define THREAD_FP4      (THREAD_CONTEXT + 0x130)
+#define THREAD_FP5      (THREAD_CONTEXT + 0x138)
+#define THREAD_FP6      (THREAD_CONTEXT + 0x140)
+#define THREAD_FP7      (THREAD_CONTEXT + 0x148)
+#define THREAD_FP8      (THREAD_CONTEXT + 0x150)
+#define THREAD_FP9      (THREAD_CONTEXT + 0x158)
+#define THREAD_FP10     (THREAD_CONTEXT + 0x160)
+#define THREAD_FP11     (THREAD_CONTEXT + 0x168)
+#define THREAD_FP12     (THREAD_CONTEXT + 0x170)
+#define THREAD_FP13     (THREAD_CONTEXT + 0x178)
+#define THREAD_FP14     (THREAD_CONTEXT + 0x180)
+#define THREAD_FP15     (THREAD_CONTEXT + 0x188)
+#define THREAD_FP16     (THREAD_CONTEXT + 0x190)
+#define THREAD_FP17     (THREAD_CONTEXT + 0x198)
+#define THREAD_FP18     (THREAD_CONTEXT + 0x1A0)
+#define THREAD_FP19     (THREAD_CONTEXT + 0x1A8)
+#define THREAD_FP20     (THREAD_CONTEXT + 0x1B0)
+#define THREAD_FP21     (THREAD_CONTEXT + 0x1B8)
+#define THREAD_FP22     (THREAD_CONTEXT + 0x1C0)
+#define THREAD_FP23     (THREAD_CONTEXT + 0x1C8)
+#define THREAD_FP24     (THREAD_CONTEXT + 0x1D0)
+#define THREAD_FP25     (THREAD_CONTEXT + 0x1D8)
+#define THREAD_FP26     (THREAD_CONTEXT + 0x1E0)
+#define THREAD_FP27     (THREAD_CONTEXT + 0x1E8)
+#define THREAD_FP28     (THREAD_CONTEXT + 0x1F0)
+#define THREAD_FP29     (THREAD_CONTEXT + 0x1F8)
+#define THREAD_FP30     (THREAD_CONTEXT + 0x200)
+#define THREAD_FP31     (THREAD_CONTEXT + 0x208)
+#endif
 
 #endif
 
diff --git a/include/ultra64/xstdio.h b/include/ultra64/xstdio.h
index 184ee49079..aa3a3957e2 100644
--- a/include/ultra64/xstdio.h
+++ b/include/ultra64/xstdio.h
@@ -4,7 +4,8 @@
 #include "stdarg.h"
 
 // IDO doesn't support long double types, improve portability for compilers supporting them
-#ifdef __sgi
+// Also make N32/N64 ABIs use double, TODO support long double in these ABIs (128-bit float)
+#if defined(__sgi) || (defined(_MIPS_SIM) && _MIPS_SIM != _ABIO32)
 #define LONG_DOUBLE_TYPE double
 #else
 #define LONG_DOUBLE_TYPE long double
diff --git a/src/gcc_fix/missing_gcc_functions.c b/src/gcc_fix/missing_gcc_functions.c
index 26fd449a64..4a3256001f 100644
--- a/src/gcc_fix/missing_gcc_functions.c
+++ b/src/gcc_fix/missing_gcc_functions.c
@@ -163,6 +163,16 @@ int __ucmpdi2(unsigned long long a, unsigned long long b) {
 
 // Compute division and modulo of 64-bit signed and unsigned integers
 
+// eabi requires the following functions, but also needs to allocate stack
+#if !defined(_MIPS_SIM)
+#define STACK_ALLOC "addiu $sp, $sp, -0x10"
+#define STACK_DEALLOC "addiu $sp, $sp,  0x10"
+#else
+#define STACK_ALLOC ""
+#define STACK_DEALLOC ""
+#endif
+
+#if !defined(_MIPS_SIM) || _MIPS_SIM == _ABIO32
 __asm__("                                   \n\
     .set push                               \n\
     .set noreorder                          \n\
@@ -172,6 +182,7 @@ __asm__("                                   \n\
 __umoddi3:                                  \n\
   .type __umoddi3, @function                \n\
   .ent __umoddi3                            \n\
+    " STACK_ALLOC "                         \n\
     sw      $a0, 0x0($sp)                   \n\
     sw      $a1, 0x4($sp)                   \n\
     sw      $a2, 0x8($sp)                   \n\
@@ -181,6 +192,7 @@ __umoddi3:                                  \n\
     dremu   $v0, $t6, $t7                   \n\
     dsll32  $v1, $v0, 0                     \n\
     dsra32  $v1, $v1, 0                     \n\
+    " STACK_DEALLOC "                       \n\
     jr      $ra                             \n\
      dsra32 $v0, $v0, 0                     \n\
   .end __umoddi3                            \n\
@@ -190,6 +202,7 @@ __umoddi3:                                  \n\
 __udivdi3:                                  \n\
   .type __udivdi3, @function                \n\
   .ent __udivdi3                            \n\
+    " STACK_ALLOC "                         \n\
     sw      $a0, 0x0($sp)                   \n\
     sw      $a1, 0x4($sp)                   \n\
     sw      $a2, 0x8($sp)                   \n\
@@ -199,6 +212,7 @@ __udivdi3:                                  \n\
     ddivu   $v0, $t6, $t7                   \n\
     dsll32  $v1, $v0, 0                     \n\
     dsra32  $v1, $v1, 0                     \n\
+    " STACK_DEALLOC "                       \n\
     jr      $ra                             \n\
      dsra32 $v0, $v0, 0                     \n\
   .end __udivdi3                            \n\
@@ -208,6 +222,7 @@ __udivdi3:                                  \n\
 __moddi3:                                   \n\
   .type __moddi3, @function                 \n\
   .ent __moddi3                             \n\
+    " STACK_ALLOC "                         \n\
     sw      $a0, 0x0($sp)                   \n\
     sw      $a1, 0x4($sp)                   \n\
     sw      $a2, 0x8($sp)                   \n\
@@ -217,6 +232,7 @@ __moddi3:                                   \n\
     drem    $v0, $t6, $t7                   \n\
     dsll32  $v1, $v0, 0                     \n\
     dsra32  $v1, $v1, 0                     \n\
+    " STACK_DEALLOC "                       \n\
     jr      $ra                             \n\
      dsra32 $v0, $v0, 0                     \n\
   .end __moddi3                             \n\
@@ -226,6 +242,7 @@ __moddi3:                                   \n\
 __divdi3:                                   \n\
   .type __divdi3, @function                 \n\
   .ent __divdi3                             \n\
+    " STACK_ALLOC "                         \n\
     sw    $a0, 0x0($sp)                     \n\
     sw    $a1, 0x4($sp)                     \n\
     sw    $a2, 0x8($sp)                     \n\
@@ -235,6 +252,7 @@ __divdi3:                                   \n\
     ddiv  $v0, $t6, $t7                     \n\
     dsll32 $v1, $v0, 0                      \n\
     dsra32 $v1, $v1, 0                      \n\
+    " STACK_DEALLOC "                       \n\
     jr    $ra                               \n\
      dsra32 $v0, $v0, 0                     \n\
   .end __divdi3                             \n\
@@ -242,3 +260,4 @@ __divdi3:                                   \n\
                                             \n\
     .set pop                                \n\
                                             \n");
+#endif
diff --git a/src/libultra/mgu/scale.s b/src/libultra/mgu/scale.s
index 5661b940cc..160b3595af 100644
--- a/src/libultra/mgu/scale.s
+++ b/src/libultra/mgu/scale.s
@@ -1,14 +1,23 @@
 #include "ultra64/asm.h"
 #include "ultra64/regdef.h"
 
+#ifdef _MIPS_SIM
+#define IS_O32 (_MIPS_SIM == _ABIO32)
+#else
+#define IS_O32 false
+#endif
+
 .text
 .align 5
 
 LEAF(guScale)
     li.s    ft0, 65536.0
-
+#if IS_O32
     mtc1    a1, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa0, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t1, ft3
 
@@ -18,8 +27,12 @@ LEAF(guScale)
     sll     t2, t1, 0x10
     sw      t2, 0x20(a0)
 
+#if IS_O32
     mtc1    a2, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa1, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t1, ft3
 
@@ -28,8 +41,12 @@ LEAF(guScale)
     andi    t2, t1, 0xFFFF
     sw      t2, 0x28(a0)
 
+#if IS_O32
     mtc1    a3, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa2, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t1, ft3
 
diff --git a/src/libultra/mgu/translate.s b/src/libultra/mgu/translate.s
index cf2d246434..9115557e15 100644
--- a/src/libultra/mgu/translate.s
+++ b/src/libultra/mgu/translate.s
@@ -1,19 +1,33 @@
 #include "ultra64/asm.h"
 #include "ultra64/regdef.h"
 
+#ifdef _MIPS_SIM
+#define IS_O32 (_MIPS_SIM == _ABIO32)
+#else
+#define IS_O32 false
+#endif
+
 .text
 .align 5
 
 LEAF(guTranslate)
     li.s    ft0, 65536.0
 
+#if IS_O32
     mtc1    a1, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa0, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t1, ft3
 
+#if IS_O32
     mtc1    a2, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa1, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t3, ft3
 
@@ -29,8 +43,12 @@ LEAF(guTranslate)
     or      t0, t0, t2
     sw      t0, 0x38(a0)
 
+#if IS_O32
     mtc1    a3, ft1
     mul.s   ft2, ft1, ft0
+#else
+    mul.s   ft2, fa2, ft0
+#endif
     trunc.w.s ft3, ft2
     mfc1    t1, ft3
 
diff --git a/src/libultra/os/createthread.c b/src/libultra/os/createthread.c
index 9332207971..fe3e36936f 100644
--- a/src/libultra/os/createthread.c
+++ b/src/libultra/os/createthread.c
@@ -15,7 +15,11 @@ void osCreateThread(OSThread* thread, OSId id, void (*entry)(void*), void* arg,
     thread->context.ra = (u64)(s32)__osCleanupThread;
 
     mask = OS_IM_ALL;
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIN32
+    thread->context.sr = (mask & OS_IM_CPU) | SR_EXL | SR_FR;
+#else
     thread->context.sr = (mask & OS_IM_CPU) | SR_EXL;
+#endif
     thread->context.rcp = (mask & RCP_IMASK) >> RCP_IMASKSHIFT;
     thread->context.fpcsr = FPCSR_FS | FPCSR_EV;
     thread->fp = 0;
diff --git a/src/libultra/os/exceptasm.s b/src/libultra/os/exceptasm.s
index 3a3919061c..7f46a70497 100644
--- a/src/libultra/os/exceptasm.s
+++ b/src/libultra/os/exceptasm.s
@@ -1,6 +1,3 @@
-#ifdef __GNUC__
-.set gp=64
-#endif
 #include "ultra64/asm.h"
 #include "ultra64/regdef.h"
 #include "ultra64/R4300.h"
@@ -98,7 +95,9 @@ LEAF(__osException)
     /* Load scratch space for thread saving */
     la      k0, __osThreadSave
     /* Save at */
+.set push; .set gp=64
     sd      AT, THREAD_AT(k0)
+.set pop
 .set at
     /* Save sr */
     MFC0(   k1, C0_SR)
@@ -107,9 +106,11 @@ LEAF(__osException)
     and     k1, k1, ~(SR_IE | SR_EXL)
     MTC0(   k1, C0_SR)
     /* Save some temp registers for use in the following */
+.set push; .set gp=64
     sd      t0, THREAD_T0(k0)
     sd      t1, THREAD_T1(k0)
     sd      t2, THREAD_T2(k0)
+.set pop
     /* Mark FPU as unused */
     sw      zero, THREAD_FP(k0)
     /* Left over from misplaced ifdef, immediately overwritten on next instruction */
@@ -119,6 +120,7 @@ savecontext:
     /* Save the previously running thread's context to be restored when it resumes */
     move    t0, k0
     lw      k0, __osRunningThread
+.set push; .set gp=64
     ld      t1, THREAD_AT(t0)
     sd      t1, THREAD_AT(k0)
     ld      t1, THREAD_SR(t0)
@@ -129,7 +131,9 @@ savecontext:
     sd      t1, THREAD_T1(k0)
     ld      t1, THREAD_T2(t0)
     sd      t1, THREAD_T2(k0)
+.set pop
 .set reorder
+.set push; .set gp=64
     sd      $2, THREAD_V0(k0)
     sd      $3, THREAD_V1(k0)
     sd      $4, THREAD_A0(k0)
@@ -159,6 +163,7 @@ savecontext:
     sd      t0, THREAD_LO(k0)
     mfhi    t0
     sd      t0, THREAD_HI(k0)
+.set pop
     lw      k1, THREAD_SR(k0)
     andi    t1, k1, SR_IMASK
     beqz    t1, savercp
@@ -220,6 +225,24 @@ endrcp:
     sdc1    $f26, THREAD_FP26(k0)
     sdc1    $f28, THREAD_FP28(k0)
     sdc1    $f30, THREAD_FP30(k0)
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIN32
+    sdc1    $f1, THREAD_FP1(k0)
+    sdc1    $f3, THREAD_FP3(k0)
+    sdc1    $f5, THREAD_FP5(k0)
+    sdc1    $f7, THREAD_FP7(k0)
+    sdc1    $f9, THREAD_FP9(k0)
+    sdc1    $f11, THREAD_FP11(k0)
+    sdc1    $f13, THREAD_FP13(k0)
+    sdc1    $f15, THREAD_FP15(k0)
+    sdc1    $f17, THREAD_FP17(k0)
+    sdc1    $f19, THREAD_FP19(k0)
+    sdc1    $f21, THREAD_FP21(k0)
+    sdc1    $f23, THREAD_FP23(k0)
+    sdc1    $f25, THREAD_FP25(k0)
+    sdc1    $f27, THREAD_FP27(k0)
+    sdc1    $f29, THREAD_FP29(k0)
+    sdc1    $f31, THREAD_FP31(k0)
+#endif
 
 handle_interrupt:
 #if ENABLE_PROFILER
@@ -769,6 +792,7 @@ LEAF(__osEnqueueAndYield)
     ori     t0, t0, SR_EXL
     sw      t0, THREAD_SR(a1)
     /* Save callee-saved registers */
+.set push; .set gp=64
     sd      s0, THREAD_S0(a1)
     sd      s1, THREAD_S1(a1)
     sd      s2, THREAD_S2(a1)
@@ -777,10 +801,11 @@ LEAF(__osEnqueueAndYield)
     sd      s5, THREAD_S5(a1)
     sd      s6, THREAD_S6(a1)
     sd      s7, THREAD_S7(a1)
-    sd      gp, THREAD_GP(a1)
+    sd      GP, THREAD_GP(a1)
     sd      sp, THREAD_SP(a1)
     sd      fp, THREAD_S8(a1)
     sd      ra, THREAD_RA(a1)
+.set pop
     sw      ra, THREAD_PC(a1)
     /* Save FPU callee-saved registers if the current thread has used the FPU */
     lw      k1, THREAD_FP(a1)
@@ -899,12 +924,16 @@ get_time_no_interrupts: /* osGetTime, but without the interrupts */
     lw      t2, %lo(__osBaseCounter)(t2)
     subu    t2, t1, t2 /* base = count - __osBaseCounter */
     lui     t3, %hi(__osCurrentTime)
+.set push; .set gp=64
     ld      t3, %lo(__osCurrentTime)(t3)
+.set pop
     addu    t1, t2, t3 /* time = base + t */
 record:
     sll     a2, a1, 3 /* numEvents * 8 for eventTimes */
     addu    a2, a2, t0 /* activeProfilerState->eventTimes[e] */
+.set push; .set gp=64
     sd      t1, (0)(a2)
+.set pop
     addu    a3, a1, t0 /* activeProfilerState->{null}[e] */
     sb      a0, (8*PROFILER_EVENT_COUNT)(a3) /* eventTypes */
     addiu   a1, a1, 1 /* numEvents++ */
@@ -948,6 +977,7 @@ LEAF(__osDispatchThread)
     MTC0(   k1, C0_SR)
     /* Restore GPRs */
 .set noat
+.set push; .set gp=64
     ld      AT, THREAD_AT(k0)
     ld      v0, THREAD_V0(k0)
     ld      v1, THREAD_V1(k0)
@@ -973,13 +1003,14 @@ LEAF(__osDispatchThread)
     ld      s7, THREAD_S7(k0)
     ld      t8, THREAD_T8(k0)
     ld      t9, THREAD_T9(k0)
-    ld      gp, THREAD_GP(k0)
+    ld      GP, THREAD_GP(k0)
     ld      sp, THREAD_SP(k0)
     ld      fp, THREAD_S8(k0)
     ld      ra, THREAD_RA(k0)
     ld      k1, THREAD_LO(k0)
     mtlo    k1
     ld      k1, THREAD_HI(k0)
+.set pop
     mthi    k1
     /* Move thread pc to EPC so that eret will return execution to where the thread left off */
     lw      k1, THREAD_PC(k0)
@@ -1008,6 +1039,24 @@ LEAF(__osDispatchThread)
     ldc1    $f26, THREAD_FP26(k0)
     ldc1    $f28, THREAD_FP28(k0)
     ldc1    $f30, THREAD_FP30(k0)
+#if defined(_MIPS_SIM) && _MIPS_SIM == _ABIN32
+    ldc1    $f1, THREAD_FP1(k0)
+    ldc1    $f3, THREAD_FP3(k0)
+    ldc1    $f5, THREAD_FP5(k0)
+    ldc1    $f7, THREAD_FP7(k0)
+    ldc1    $f9, THREAD_FP9(k0)
+    ldc1    $f11, THREAD_FP11(k0)
+    ldc1    $f13, THREAD_FP13(k0)
+    ldc1    $f15, THREAD_FP15(k0)
+    ldc1    $f17, THREAD_FP17(k0)
+    ldc1    $f19, THREAD_FP19(k0)
+    ldc1    $f21, THREAD_FP21(k0)
+    ldc1    $f23, THREAD_FP23(k0)
+    ldc1    $f25, THREAD_FP25(k0)
+    ldc1    $f27, THREAD_FP27(k0)
+    ldc1    $f29, THREAD_FP29(k0)
+    ldc1    $f31, THREAD_FP31(k0)
+#endif
 1:
     /* Restore RCP interrupt mask, masking out any RCP interrupts that */
     /* are not also enabled in the global interrupt mask */
diff --git a/src/libultra/os/initialize.c b/src/libultra/os/initialize.c
index 53b84d4334..1293b64a88 100644
--- a/src/libultra/os/initialize.c
+++ b/src/libultra/os/initialize.c
@@ -59,8 +59,15 @@ void OSINITIALIZE_FUNC(void) {
 #endif
 
     __osFinalrom = true;
+
+#if defined(_MIPS_SIM) && (_MIPS_SIM == _ABIN32) // N32 sets FR
+    __osSetSR(__osGetSR() | SR_CU1 | SR_FR);
+#else // O32 and EABI don't set FR
     __osSetSR(__osGetSR() | SR_CU1);
+#endif
+
     __osSetFpcCsr(FPCSR_FS | FPCSR_EV | FPCSR_RM_RN);
+
 #if LIBULTRA_VERSION >= LIBULTRA_VERSION_K
     __osSetWatchLo(0x04900000);
 #endif

From 05dfc23df44995b66cfd1fa8f4ffd8c7bd032e8a Mon Sep 17 00:00:00 2001
From: Thar0 <17233964+Thar0@users.noreply.github.com>
Date: Fri, 19 Jul 2024 21:23:36 +0100
Subject: [PATCH 2/5] Default is EABI32

---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 2d1f558307..72270a941e 100644
--- a/Makefile
+++ b/Makefile
@@ -45,7 +45,7 @@ REGION ?= US
 # This may also be used to disable debug features on debug ROMs by setting DEBUG_FEATURES to 0
 DEBUG_FEATURES ?= 1
 # MIPS ABI, can be one of "32", "n32" or "eabi"
-ABI := 32
+ABI := eabi
 
 # Version-specific settings
 REGIONAL_CHECKSUM := 0

From 091544d0fccb1c3b6a5e95587d67d270b4e2e208 Mon Sep 17 00:00:00 2001
From: Tharo <17233964+Thar0@users.noreply.github.com>
Date: Wed, 26 Nov 2025 22:51:08 +0000
Subject: [PATCH 3/5] Try fix mgu register name error

---
 include/ultra64/regdef.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/include/ultra64/regdef.h b/include/ultra64/regdef.h
index 127846182d..94e79bbaae 100644
--- a/include/ultra64/regdef.h
+++ b/include/ultra64/regdef.h
@@ -70,8 +70,12 @@
 #define fa1f    $f15
 #define fa2     $f16
 #define fa2f    $f17
+#define ft4     $f16
+#define ft4f    $f17
 #define fa3     $f18
 #define fa3f    $f19
+#define ft5     $f16
+#define ft5f    $f17
 #define fs0     $f20
 #define fs0f    $f21
 #define fs1     $f22

From 287a0c3dadfb074b07cee0cfc8f41529bf1fe62e Mon Sep 17 00:00:00 2001
From: Tharo <17233964+Thar0@users.noreply.github.com>
Date: Wed, 26 Nov 2025 23:40:12 +0000
Subject: [PATCH 4/5] Restore comment

---
 Makefile | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/Makefile b/Makefile
index 72270a941e..445ce30afb 100644
--- a/Makefile
+++ b/Makefile
@@ -6,6 +6,11 @@ SHELL = /usr/bin/env bash
 
 #### Build options ####
 
+# Build options can be changed by modifying them below, or by appending 'SETTING=value' to all 'make' commands
+# (e.g. 'make setup VERSION=ntsc-1.0' and 'make VERSION=ntsc-1.0' to build the NTSC 1.0 version).
+# Alternatively, you can create a file called .make_options.mk (gitignored by default) and add 'SETTING=value'
+# there to avoid modifying the Makefile directly.
+
 -include .make_options.mk
 
 COMPILER ?= gcc

From e11e587e3aa51fe5a97f4456a03024db4bf6a542 Mon Sep 17 00:00:00 2001
From: Tharo <17233964+Thar0@users.noreply.github.com>
Date: Thu, 27 Nov 2025 00:10:08 +0000
Subject: [PATCH 5/5] Make o32 default again, warn about bad emulators

---
 Makefile | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 445ce30afb..8a90a5c3e5 100644
--- a/Makefile
+++ b/Makefile
@@ -50,7 +50,8 @@ REGION ?= US
 # This may also be used to disable debug features on debug ROMs by setting DEBUG_FEATURES to 0
 DEBUG_FEATURES ?= 1
 # MIPS ABI, can be one of "32", "n32" or "eabi"
-ABI := eabi
+# Note n32 and/or eabi may break some old emulators or emulator versions
+ABI := 32
 
 # Version-specific settings
 REGIONAL_CHECKSUM := 0