gpsp/arm/arm_stub.S

939 lines
39 KiB
ArmAsm

.align 2
.global arm_update_gba_arm
.global arm_update_gba_thumb
.global arm_update_gba_idle_arm
.global arm_update_gba_idle_thumb
.global arm_indirect_branch_arm
.global arm_indirect_branch_thumb
.global arm_indirect_branch_dual_arm
.global arm_indirect_branch_dual_thumb
.global execute_arm_translate
.global execute_store_u8
.global execute_store_u16
.global execute_store_u32
.global execute_store_u32_safe
.global execute_load_u8
.global execute_load_s8
.global execute_load_u16
.global execute_load_s16
.global execute_load_u32
.global execute_store_cpsr
.global execute_read_spsr
.global execute_store_spsr
.global execute_spsr_restore
.global execute_swi_arm
.global execute_swi_thumb
.global execute_patch_bios_read
.global execute_patch_bios_protect
.global execute_bios_ptr_protected
.global execute_bios_rom_ptr
.global invalidate_icache_region
.global invalidate_cache_region
.global memory_map_read
.global memory_map_write
.global reg
#define REG_BASE_OFFSET 1024
#define REG_R0 (REG_BASE_OFFSET + (0 * 4))
#define REG_R1 (REG_BASE_OFFSET + (1 * 4))
#define REG_R2 (REG_BASE_OFFSET + (2 * 4))
#define REG_R3 (REG_BASE_OFFSET + (3 * 4))
#define REG_R4 (REG_BASE_OFFSET + (4 * 4))
#define REG_R5 (REG_BASE_OFFSET + (5 * 4))
#define REG_R6 (REG_BASE_OFFSET + (6 * 4))
#define REG_R7 (REG_BASE_OFFSET + (7 * 4))
#define REG_R8 (REG_BASE_OFFSET + (8 * 4))
#define REG_R9 (REG_BASE_OFFSET + (9 * 4))
#define REG_R10 (REG_BASE_OFFSET + (10 * 4))
#define REG_R11 (REG_BASE_OFFSET + (11 * 4))
#define REG_R12 (REG_BASE_OFFSET + (12 * 4))
#define REG_R13 (REG_BASE_OFFSET + (13 * 4))
#define REG_R14 (REG_BASE_OFFSET + (14 * 4))
#define REG_SP (REG_BASE_OFFSET + (13 * 4))
#define REG_LR (REG_BASE_OFFSET + (14 * 4))
#define REG_PC (REG_BASE_OFFSET + (15 * 4))
#define REG_N_FLAG (REG_BASE_OFFSET + (16 * 4))
#define REG_Z_FLAG (REG_BASE_OFFSET + (17 * 4))
#define REG_C_FLAG (REG_BASE_OFFSET + (18 * 4))
#define REG_V_FLAG (REG_BASE_OFFSET + (19 * 4))
#define REG_CPSR (REG_BASE_OFFSET + (20 * 4))
#define REG_SAVE (REG_BASE_OFFSET + (21 * 4))
#define REG_SAVE2 (REG_BASE_OFFSET + (22 * 4))
#define REG_SAVE3 (REG_BASE_OFFSET + (23 * 4))
#define CPU_MODE (REG_BASE_OFFSET + (29 * 4))
#define CPU_HALT_STATE (REG_BASE_OFFSET + (30 * 4))
#define CHANGED_PC_STATUS (REG_BASE_OFFSET + (31 * 4))
#define reg_a0 r0
#define reg_a1 r1
#define reg_a2 r2
#define reg_s0 r9
#define reg_base sp
#define reg_flags r11
#define reg_cycles r12
#define reg_x0 r3
#define reg_x1 r4
#define reg_x2 r5
#define reg_x3 r6
#define reg_x4 r7
#define reg_x5 r8
#define MODE_SUPERVISOR 3
#ifdef __ARM_ARCH_7A__
#define extract_u16(rd, rs) \
uxth rd, rs
#else
#define extract_u16(rd, rs) \
bic rd, rs, #0xff000000 ;\
bic rd, rd, #0x00ff0000
#endif
@ Will load the register set from memory into the appropriate cached registers.
@ See arm_emit.h for listing explanation.
#define load_registers_arm() ;\
ldr reg_x0, [reg_base, #REG_R0] ;\
ldr reg_x1, [reg_base, #REG_R1] ;\
ldr reg_x2, [reg_base, #REG_R6] ;\
ldr reg_x3, [reg_base, #REG_R9] ;\
ldr reg_x4, [reg_base, #REG_R12] ;\
ldr reg_x5, [reg_base, #REG_R14] ;\
#define load_registers_thumb() ;\
ldr reg_x0, [reg_base, #REG_R0] ;\
ldr reg_x1, [reg_base, #REG_R1] ;\
ldr reg_x2, [reg_base, #REG_R2] ;\
ldr reg_x3, [reg_base, #REG_R3] ;\
ldr reg_x4, [reg_base, #REG_R4] ;\
ldr reg_x5, [reg_base, #REG_R5] ;\
@ Will store the register set from cached registers back to memory.
#define store_registers_arm() ;\
str reg_x0, [reg_base, #REG_R0] ;\
str reg_x1, [reg_base, #REG_R1] ;\
str reg_x2, [reg_base, #REG_R6] ;\
str reg_x3, [reg_base, #REG_R9] ;\
str reg_x4, [reg_base, #REG_R12] ;\
str reg_x5, [reg_base, #REG_R14] ;\
#define store_registers_thumb() ;\
str reg_x0, [reg_base, #REG_R0] ;\
str reg_x1, [reg_base, #REG_R1] ;\
str reg_x2, [reg_base, #REG_R2] ;\
str reg_x3, [reg_base, #REG_R3] ;\
str reg_x4, [reg_base, #REG_R4] ;\
str reg_x5, [reg_base, #REG_R5] ;\
@ Returns an updated persistent cpsr with the cached flags register.
@ Uses reg as a temporary register and returns the CPSR here.
#define collapse_flags_no_update(reg) ;\
ldr reg, [reg_base, #REG_CPSR] /* reg = cpsr */;\
bic reg, reg, #0xF0000000 /* clear ALU flags in cpsr */;\
and reg_flags, reg_flags, #0xF0000000 /* clear non-ALU flags */;\
orr reg, reg, reg_flags /* update cpsr with ALU flags */;\
@ Updates cpsr using the above macro.
#define collapse_flags(reg) ;\
collapse_flags_no_update(reg) ;\
str reg, [reg_base, #REG_CPSR] ;\
@ Loads the saved flags register from the persistent cpsr.
#define extract_flags() ;\
ldr reg_flags, [reg_base, #REG_CPSR] ;\
msr cpsr_f, reg_flags ;\
#define save_flags() ;\
mrs reg_flags, cpsr ;\
#define restore_flags() ;\
msr cpsr_f, reg_flags ;\
#ifdef __ARM_EABI__
@ must align stack
#define call_c_saved_regs r2, r3, r12, lr
#else
#define call_c_saved_regs r3, r12, lr
#endif
@ Calls a C function - all caller save registers which are important to the
@ dynarec and to returning from this function are saved.
#define call_c_function(function) ;\
stmdb sp!, { call_c_saved_regs } ;\
bl function ;\
ldmia sp!, { call_c_saved_regs } ;\
@ Update the GBA hardware (video, sound, input, etc)
@ Input:
@ r0: current PC
#define return_straight() ;\
bx lr ;\
#define return_add() ;\
add pc, lr, #4 ;\
#define load_pc_straight() ;\
ldr r0, [lr, #-8] ;\
#define load_pc_add() ;\
ldr r0, [lr] ;\
#define arm_update_gba_builder(name, mode, return_op) ;\
;\
arm_update_gba_##name: ;\
load_pc_##return_op() ;\
str r0, [reg_base, #REG_PC] /* write out the PC */;\
;\
save_flags() ;\
collapse_flags(r0) /* update the flags */;\
;\
store_registers_##mode() /* save out registers */;\
call_c_function(update_gba) /* update GBA state */;\
;\
mvn reg_cycles, r0 /* load new cycle count */;\
;\
ldr r0, [reg_base, #CHANGED_PC_STATUS] /* load PC changed status */;\
cmp r0, #0 /* see if PC has changed */;\
beq 1f /* if not return */;\
;\
ldr r0, [reg_base, #REG_PC] /* load new PC */;\
ldr r1, [reg_base, #REG_CPSR] /* r1 = flags */;\
tst r1, #0x20 /* see if Thumb bit is set */;\
bne 2f /* if so load Thumb PC */;\
;\
load_registers_arm() /* load ARM regs */;\
call_c_function(block_lookup_address_arm) ;\
restore_flags() ;\
bx r0 /* jump to new ARM block */;\
;\
1: ;\
load_registers_##mode() /* reload registers */;\
restore_flags() ;\
return_##return_op() ;\
;\
2: ;\
load_registers_thumb() /* load Thumb regs */;\
call_c_function(block_lookup_address_thumb) ;\
restore_flags() ;\
bx r0 /* jump to new ARM block */;\
arm_update_gba_builder(arm, arm, straight)
arm_update_gba_builder(thumb, thumb, straight)
arm_update_gba_builder(idle_arm, arm, add)
arm_update_gba_builder(idle_thumb, thumb, add)
@ These are b stubs for performing indirect branches. They are not
@ linked to and don't return, instead they link elsewhere.
@ Input:
@ r0: PC to branch to
arm_indirect_branch_arm:
save_flags()
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0
arm_indirect_branch_thumb:
save_flags()
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0
arm_indirect_branch_dual_arm:
save_flags()
tst r0, #0x01 @ check lower bit
bne 1f @ if set going to Thumb mode
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0 @ return
1:
bic r0, r0, #0x01
store_registers_arm() @ save out ARM registers
load_registers_thumb() @ load in Thumb registers
ldr r1, [reg_base, #REG_CPSR] @ load cpsr
orr r1, r1, #0x20 @ set Thumb mode
str r1, [reg_base, #REG_CPSR] @ store flags
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0 @ return
arm_indirect_branch_dual_thumb:
save_flags()
tst r0, #0x01 @ check lower bit
beq 1f @ if set going to ARM mode
bic r0, r0, #0x01
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0 @ return
1:
store_registers_thumb() @ save out Thumb registers
load_registers_arm() @ load in ARM registers
ldr r1, [reg_base, #REG_CPSR] @ load cpsr
bic r1, r1, #0x20 @ clear Thumb mode
str r1, [reg_base, #REG_CPSR] @ store flags
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0 @ return
@ Update the cpsr.
@ Input:
@ r0: new cpsr value
@ r1: bitmask of which bits in cpsr to update
@ r2: current PC
execute_store_cpsr:
save_flags()
and reg_flags, r0, r1 @ reg_flags = new_cpsr & store_mask
ldr r0, [reg_base, #REG_CPSR] @ r0 = cpsr
bic r0, r0, r1 @ r0 = cpsr & ~store_mask
orr reg_flags, reg_flags, r0 @ reg_flags = new_cpsr | cpsr
mov r0, reg_flags @ also put new cpsr in r0
store_registers_arm() @ save ARM registers
ldr r2, [lr] @ r2 = pc
call_c_function(execute_store_cpsr_body)
load_registers_arm() @ restore ARM registers
cmp r0, #0 @ check new PC
beq 1f @ if it's zero, return
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0 @ return to new ARM address
1:
restore_flags()
add pc, lr, #4 @ return
@ Update the current spsr.
@ Input:
@ r0: new cpsr value
@ r1: bitmask of which bits in spsr to update
execute_store_spsr:
ldr r1, =spsr @ r1 = spsr
ldr r2, [reg_base, #CPU_MODE] @ r2 = CPU_MODE
str r0, [r1, r2, lsl #2] @ spsr[CPU_MODE] = new_spsr
bx lr
@ Read the current spsr.
@ Output:
@ r0: spsr
execute_read_spsr:
ldr r0, =spsr @ r0 = spsr
ldr r1, [reg_base, #CPU_MODE] @ r1 = CPU_MODE
ldr r0, [r0, r1, lsl #2] @ r0 = spsr[CPU_MODE]
bx lr @ return
@ Restore the cpsr from the mode spsr and mode shift.
@ Input:
@ r0: current pc
execute_spsr_restore:
save_flags()
ldr r1, =spsr @ r1 = spsr
ldr r2, [reg_base, #CPU_MODE] @ r2 = cpu_mode
ldr r1, [r1, r2, lsl #2] @ r1 = spsr[cpu_mode] (new cpsr)
str r1, [reg_base, #REG_CPSR] @ update cpsr
mov reg_flags, r1 @ also, update shadow flags
@ This function call will pass r0 (address) and return it.
store_registers_arm() @ save ARM registers
call_c_function(execute_spsr_restore_body)
ldr r1, [reg_base, #REG_CPSR] @ r1 = cpsr
tst r1, #0x20 @ see if Thumb mode is set
bne 2f @ if so handle it
load_registers_arm() @ restore ARM registers
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0
2:
load_registers_thumb() @ load Thumb registers
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0
@ Setup the mode transition work for calling an SWI.
@ Input:
@ r0: current pc
#define execute_swi_builder(mode) ;\
;\
execute_swi_##mode: ;\
save_flags() ;\
ldr r1, =reg_mode /* r1 = reg_mode */;\
/* reg_mode[MODE_SUPERVISOR][6] = pc */;\
ldr r0, [lr] /* load PC */;\
str r0, [r1, #((MODE_SUPERVISOR * (7 * 4)) + (6 * 4))] ;\
collapse_flags_no_update(r0) /* r0 = cpsr */;\
ldr r1, =spsr /* r1 = spsr */;\
str r0, [r1, #(MODE_SUPERVISOR * 4)] /* spsr[MODE_SUPERVISOR] = cpsr */;\
bic r0, r0, #0x3F /* clear mode flag in r0 */;\
orr r0, r0, #0x13 /* set to supervisor mode */;\
str r0, [reg_base, #REG_CPSR] /* update cpsr */;\
;\
call_c_function(bios_region_read_allow) ;\
;\
mov r0, #MODE_SUPERVISOR ;\
;\
store_registers_##mode() /* store regs for mode */;\
call_c_function(set_cpu_mode) /* set the CPU mode to svsr */;\
load_registers_arm() /* load ARM regs */;\
;\
restore_flags() ;\
add pc, lr, #4 /* return */;\
execute_swi_builder(arm)
execute_swi_builder(thumb)
@ Wrapper for calling SWI functions in C (or can implement some in ASM if
@ desired)
#define execute_swi_function_builder(swi_function, mode) ;\
;\
.global execute_swi_hle_##swi_function##_##mode ;\
execute_swi_hle_##swi_function##_##mode: ;\
save_flags() ;\
store_registers_##mode() ;\
call_c_function(execute_swi_hle_##swi_function##_c) ;\
load_registers_##mode() ;\
restore_flags() ;\
bx lr ;\
execute_swi_function_builder(div, arm)
execute_swi_function_builder(div, thumb)
@ Start program execution. Normally the mode should be Thumb and the
@ PC should be 0x8000000, however if a save state is preloaded this
@ will be different.
@ Input:
@ r0: initial value for cycle counter
@ Uses sp as reg_base; must hold consistently true.
execute_arm_translate:
sub sp, sp, #0x100 @ allocate room for register data
mvn reg_cycles, r0 @ load cycle counter
mov r0, reg_base @ load reg_base into first param
call_c_function(move_reg) @ make reg_base the new reg ptr
sub sp, sp, #REG_BASE_OFFSET @ allocate room for ptr table
bl load_ptr_read_function_table @ load read function ptr table
ldr r0, [reg_base, #REG_PC] @ r0 = current pc
ldr r1, [reg_base, #REG_CPSR] @ r1 = flags
tst r1, #0x20 @ see if Thumb bit is set
bne 1f @ if so lookup thumb
load_registers_arm() @ load ARM registers
call_c_function(block_lookup_address_arm)
extract_flags() @ load flags
bx r0 @ jump to first ARM block
1:
load_registers_thumb() @ load Thumb registers
call_c_function(block_lookup_address_thumb)
extract_flags() @ load flags
bx r0 @ jump to first Thumb block
@ Write out to memory.
@ Input:
@ r0: address
@ r1: value
@ r2: current pc
#define execute_store_body(store_type, store_op) ;\
save_flags() ;\
stmdb sp!, { lr } /* save lr */;\
tst r0, #0xF0000000 /* make sure address is in range */;\
bne ext_store_u##store_type /* if not do ext store */;\
;\
ldr r2, =memory_map_write /* r2 = memory_map_write */;\
mov lr, r0, lsr #15 /* lr = page index of address */;\
ldr r2, [r2, lr, lsl #2] /* r2 = memory page */;\
;\
cmp r2, #0 /* see if map is ext */;\
beq ext_store_u##store_type /* if so do ext store */;\
;\
mov r0, r0, lsl #17 /* isolate bottom 15 bits in top */;\
mov r0, r0, lsr #17 /* like performing and 0x7FFF */;\
store_op r1, [r2, r0] /* store result */;\
#define store_align_8() ;\
and r1, r1, #0xff ;\
#define store_align_16() ;\
bic r0, r0, #0x01 ;\
extract_u16(r1, r1) ;\
#define store_align_32() ;\
bic r0, r0, #0x03 ;\
#define execute_store_builder(store_type, store_op, load_op) ;\
;\
execute_store_u##store_type: ;\
execute_store_body(store_type, store_op) ;\
sub r2, r2, #0x8000 /* Pointer to code status data */;\
load_op r0, [r2, r0] /* check code flag */;\
;\
cmp r0, #0 /* see if it's not 0 */;\
bne 2f /* if so perform smc write */;\
ldmia sp!, { lr } /* restore lr */;\
restore_flags() ;\
add pc, lr, #4 /* return */;\
;\
2: ;\
ldmia sp!, { lr } /* restore lr */;\
ldr r0, [lr] /* load PC */;\
str r0, [reg_base, #REG_PC] /* write out PC */;\
b smc_write /* perform smc write */;\
;\
ext_store_u##store_type: ;\
ldmia sp!, { lr } /* pop lr off of stack */;\
ldr r2, [lr] /* load PC */;\
str r2, [reg_base, #REG_PC] /* write out PC */;\
store_align_##store_type() ;\
call_c_function(write_memory##store_type) ;\
b write_epilogue /* handle additional write stuff */;\
execute_store_builder(8, strb, ldrb)
execute_store_builder(16, strh, ldrh)
execute_store_builder(32, str, ldr)
execute_store_u32_safe:
execute_store_body(32_safe, str)
restore_flags()
ldmia sp!, { pc } @ return
ext_store_u32_safe:
ldmia sp!, { lr } @ Restore lr
call_c_function(write_memory32) @ Perform 32bit store
restore_flags()
bx lr @ Return
write_epilogue:
cmp r0, #0 @ check if the write rose an alert
beq 4f @ if not we can exit
collapse_flags(r1) @ interrupt needs current flags
cmp r0, #2 @ see if the alert is due to SMC
beq smc_write @ if so, goto SMC handler
ldr r1, [reg_base, #REG_CPSR] @ r1 = cpsr
tst r1, #0x20 @ see if Thumb bit is set
bne 1f @ if so do Thumb update
store_registers_arm() @ save ARM registers
3:
bl update_gba @ update GBA until CPU isn't halted
mvn reg_cycles, r0 @ load new cycle count
ldr r0, [reg_base, #REG_PC] @ load new PC
ldr r1, [reg_base, #REG_CPSR] @ r1 = flags
tst r1, #0x20 @ see if Thumb bit is set
bne 2f
load_registers_arm()
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0 @ jump to new ARM block
1:
store_registers_thumb() @ save Thumb registers
b 3b
2:
load_registers_thumb()
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0 @ jump to new Thumb block
4:
restore_flags()
add pc, lr, #4 @ return
smc_write:
call_c_function(flush_translation_cache_ram)
lookup_pc:
ldr r0, [reg_base, #REG_PC] @ r0 = new pc
ldr r1, [reg_base, #REG_CPSR] @ r1 = flags
tst r1, #0x20 @ see if Thumb bit is set
beq lookup_pc_arm @ if not lookup ARM
lookup_pc_thumb:
call_c_function(block_lookup_address_thumb)
restore_flags()
bx r0 @ jump to new Thumb block
lookup_pc_arm:
call_c_function(block_lookup_address_arm)
restore_flags()
bx r0 @ jump to new ARM block
#define sign_extend_u8(reg)
#define sign_extend_u16(reg)
#define sign_extend_u32(reg)
#define sign_extend_s8(reg) ;\
mov reg, reg, lsl #24 /* shift reg into upper 8bits */;\
mov reg, reg, asr #24 /* shift down, sign extending */;\
#define sign_extend_s16(reg) ;\
mov reg, reg, lsl #16 /* shift reg into upper 16bits */;\
mov reg, reg, asr #16 /* shift down, sign extending */;\
#define execute_load_op_u8(load_op) ;\
mov r0, r0, lsl #17 ;\
load_op r0, [r2, r0, lsr #17] ;\
#define execute_load_op_s8(load_op) ;\
mov r0, r0, lsl #17 ;\
mov r0, r0, lsr #17 ;\
load_op r0, [r2, r0] ;\
#define execute_load_op_u16(load_op) ;\
execute_load_op_s8(load_op) ;\
#define execute_load_op_s16(load_op) ;\
execute_load_op_s8(load_op) ;\
#define execute_load_op_u16(load_op) ;\
execute_load_op_s8(load_op) ;\
#define execute_load_op_u32(load_op) ;\
execute_load_op_u8(load_op) ;\
#define execute_load_builder(load_type, load_function, load_op, mask) ;\
;\
execute_load_##load_type: ;\
save_flags() ;\
tst r0, mask /* make sure address is in range */;\
bne ext_load_##load_type /* if not do ext load */;\
;\
ldr r2, =memory_map_read /* r2 = memory_map_read */;\
mov r1, r0, lsr #15 /* r1 = page index of address */;\
ldr r2, [r2, r1, lsl #2] /* r2 = memory page */;\
;\
cmp r2, #0 /* see if map is ext */;\
beq ext_load_##load_type /* if so do ext load */;\
;\
execute_load_op_##load_type(load_op) ;\
restore_flags() ;\
add pc, lr, #4 /* return */;\
;\
ext_load_##load_type: ;\
ldr r1, [lr] /* r1 = PC */;\
str r1, [reg_base, #REG_PC] /* update PC */;\
call_c_function(read_memory##load_function) ;\
sign_extend_##load_type(r0) /* sign extend result */;\
restore_flags() ;\
add pc, lr, #4 /* return */;\
execute_load_builder(u8, 8, ldrneb, #0xF0000000)
execute_load_builder(s8, 8, ldrnesb, #0xF0000000)
execute_load_builder(u16, 16, ldrneh, #0xF0000001)
execute_load_builder(s16, 16_signed, ldrnesh, #0xF0000001)
execute_load_builder(u32, 32, ldrne, #0xF0000000)
#define execute_ptr_builder(region, ptr, bits) ;\
;\
execute_##region##_ptr: ;\
ldr r1, =(ptr) /* load region ptr */;\
mov r0, r0, lsl #(32 - bits) /* isolate bottom bits */;\
mov r0, r0, lsr #(32 - bits) ;\
bx lr /* return */;\
execute_bios_ptr_protected:
ldr r1, =bios_read_protect @ load bios read ptr
and r0, r0, #0x03 @ only want bottom 2 bits
bx lr @ return
@ address = (address & 0x7FFF) + ((address & 0x38000) * 2) + 0x8000;
execute_ewram_ptr:
ldr r1, =(ewram + 0x8000) @ load ewram read ptr
mov r2, r0, lsl #17 @ isolate bottom 15 bits
mov r2, r2, lsr #17
and r0, r0, #0x38000 @ isolate top 2 bits
add r0, r2, r0, lsl #1 @ add top 2 bits * 2 to bottom 15
bx lr @ return
@ u32 gamepak_index = address >> 15;
@ u8 *map = memory_map_read[gamepak_index];
@ if(map == NULL)
@ map = load_gamepak_page(gamepak_index & 0x3FF);
@ value = address##type(map, address & 0x7FFF)
execute_gamepak_ptr:
ldr r1, =memory_map_read @ load memory_map_read
mov r2, r0, lsr #15 @ isolate top 17 bits
ldr r1, [r1, r2, lsl #2] @ load memory map read ptr
save_flags()
cmp r1, #0 @ see if map entry is NULL
bne 2f @ if not resume
stmdb sp!, { r0 } @ save r0 on stack
mov r2, r2, lsl #20 @ isolate page index
mov r0, r2, lsr #20
call_c_function(load_gamepak_page) @ read new page into r0
mov r1, r0 @ new map = return
ldmia sp!, { r0 } @ restore r0
2:
mov r0, r0, lsl #17 @ isolate bottom 15 bits
mov r0, r0, lsr #17
restore_flags()
bx lr @ return
@ These will store the result in a pointer, then pass that pointer.
execute_eeprom_ptr:
save_flags()
call_c_function(read_eeprom) @ load EEPROM result
add r1, reg_base, #(REG_SAVE & 0xFF00)
add r1, r1, #(REG_SAVE & 0xFF)
strh r0, [r1] @ write result out
mov r0, #0 @ zero out address
restore_flags()
bx lr @ return
execute_backup_ptr:
save_flags()
mov r0, r0, lsl #16 @ only want top 16 bits
mov r0, r0, lsr #16
call_c_function(read_backup) @ load backup result
add r1, reg_base, #(REG_SAVE & 0xFF00)
add r1, r1, #(REG_SAVE & 0xFF)
strb r0, [r1] @ write result out
mov r0, #0 @ zero out address
restore_flags()
bx lr @ return
execute_open_ptr:
ldr r1, [reg_base, #REG_CPSR] @ r1 = cpsr
save_flags()
stmdb sp!, { r0 } @ save r0
ldr r0, [lr, #-4] @ r0 = current PC
tst r1, #0x20 @ see if Thumb bit is set
bne 1f @ if so load Thumb op
call_c_function(read_memory32) @ read open address
add r1, reg_base, #((REG_SAVE + 4) & 0xFF00)
add r1, r1, #((REG_SAVE + 4) & 0xFF)
add r1, r1, reg_base
str r0, [r1] @ write out
ldmia sp!, { r0 } @ restore r0
and r0, r0, #0x03 @ isolate bottom 2 bits
restore_flags()
bx lr
1:
call_c_function(read_memory16) @ read open address
orr r0, r0, r0, lsl #16 @ duplicate opcode over halves
add r1, reg_base, #((REG_SAVE + 4) & 0xFF00)
add r1, r1, #((REG_SAVE + 4) & 0xFF)
add r1, r1, reg_base
str r0, [r1] @ write out
ldmia sp!, { r0 } @ restore r0
and r0, r0, #0x03 @ isolate bottom 2 bits
restore_flags();
bx lr
execute_ptr_builder(bios_rom, bios_rom, 14)
execute_ptr_builder(iwram, iwram + 0x8000, 15)
execute_ptr_builder(vram, vram, 17)
execute_ptr_builder(oam_ram, oam_ram, 10)
execute_ptr_builder(io_registers, io_registers, 10)
execute_ptr_builder(palette_ram, palette_ram, 10)
ptr_read_function_table:
.word execute_bios_ptr_protected @ 0x00: BIOS
.word execute_open_ptr @ 0x01: open
.word execute_ewram_ptr @ 0x02: ewram
.word execute_iwram_ptr @ 0x03: iwram
.word execute_io_registers_ptr @ 0x04: I/O registers
.word execute_palette_ram_ptr @ 0x05: palette RAM
.word execute_vram_ptr @ 0x06: vram
.word execute_oam_ram_ptr @ 0x07: oam RAM
.word execute_gamepak_ptr @ 0x08: gamepak
.word execute_gamepak_ptr @ 0x09: gamepak
.word execute_gamepak_ptr @ 0x0A: gamepak
.word execute_gamepak_ptr @ 0x0B: gamepak
.word execute_gamepak_ptr @ 0x0C: gamepak
.word execute_eeprom_ptr @ 0x0D: EEPROM
.word execute_backup_ptr @ 0x0E: backup
.rept (256 - 15) @ 0x0F - 0xFF: open
.word execute_open_ptr
.endr
@ Setup the read function table.
@ Load this onto the the stack; assume we're free to use r3
load_ptr_read_function_table:
mov r0, #256 @ 256 elements
ldr r1, =ptr_read_function_table @ r0 = ptr_read_function_table
mov r2, sp @ load here
2:
ldr r3, [r1], #4 @ read pointer
str r3, [r2], #4 @ write pointer
subs r0, r0, #1 @ goto next iteration
bne 2b
bx lr
@ Patch the read function table to allow for BIOS reads.
execute_patch_bios_read:
ldr r1, =reg @ r1 = reg
ldr r0, =execute_bios_rom_ptr @ r0 = patch function
ldr r1, [r1]
str r0, [r1, #-REG_BASE_OFFSET]
bx lr
@ Patch the read function table to allow for BIOS reads.
execute_patch_bios_protect:
ldr r1, =reg @ r1 = reg
ldr r0, =execute_bios_ptr_protected @ r0 = patch function
ldr r1, [r1]
str r0, [r1, #-REG_BASE_OFFSET]
bx lr
#define save_reg_scratch(reg) ;\
ldr r2, [reg_base, #(REG_BASE_OFFSET + (reg * 4))] ;\
str r2, [reg_base, #(REG_BASE_OFFSET + (reg * 4) + 128)] ;\
#define restore_reg_scratch(reg) ;\
ldr r2, [reg_base, #(REG_BASE_OFFSET + (reg * 4) + 128)] ;\
str r2, [reg_base, #(REG_BASE_OFFSET + (reg * 4))] ;\
#define scratch_regs_thumb(type) ;\
type##_reg_scratch(0) ;\
type##_reg_scratch(1) ;\
type##_reg_scratch(2) ;\
type##_reg_scratch(3) ;\
type##_reg_scratch(4) ;\
type##_reg_scratch(5) ;\
#define scratch_regs_arm(type) ;\
type##_reg_scratch(0) ;\
type##_reg_scratch(1) ;\
type##_reg_scratch(6) ;\
type##_reg_scratch(9) ;\
type##_reg_scratch(12) ;\
type##_reg_scratch(14) ;\
.pool
.comm memory_map_read 0x8000
.comm memory_map_write 0x8000