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tinygo/targets/gameboy-advance.s

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targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
.section .init
.global _start
.align
.arm
_start:
b start_vector
fix GBA ROM header Populate the GBA ROM header so that emulators and physical Game Boy Advance consoles recognize the ROM as a valid game. Note: The reserve space at the end of the header was hand-tuned. Why this magic value?
4 years ago
// ROM header
.byte 0x24,0xff,0xae,0x51,0x69,0x9a,0xa2,0x21,0x3d,0x84,0x82,0x0a,0x84,0xe4,0x09,0xad
.byte 0x11,0x24,0x8b,0x98,0xc0,0x81,0x7f,0x21,0xa3,0x52,0xbe,0x19,0x93,0x09,0xce,0x20
.byte 0x10,0x46,0x4a,0x4a,0xf8,0x27,0x31,0xec,0x58,0xc7,0xe8,0x33,0x82,0xe3,0xce,0xbf
.byte 0x85,0xf4,0xdf,0x94,0xce,0x4b,0x09,0xc1,0x94,0x56,0x8a,0xc0,0x13,0x72,0xa7,0xfc
.byte 0x9f,0x84,0x4d,0x73,0xa3,0xca,0x9a,0x61,0x58,0x97,0xa3,0x27,0xfc,0x03,0x98,0x76
.byte 0x23,0x1d,0xc7,0x61,0x03,0x04,0xae,0x56,0xbf,0x38,0x84,0x00,0x40,0xa7,0x0e,0xfd
.byte 0xff,0x52,0xfe,0x03,0x6f,0x95,0x30,0xf1,0x97,0xfb,0xc0,0x85,0x60,0xd6,0x80,0x25
.byte 0xa9,0x63,0xbe,0x03,0x01,0x4e,0x38,0xe2,0xf9,0xa2,0x34,0xff,0xbb,0x3e,0x03,0x44
.byte 0x78,0x00,0x90,0xcb,0x88,0x11,0x3a,0x94,0x65,0xc0,0x7c,0x63,0x87,0xf0,0x3c,0xaf
.byte 0xd6,0x25,0xe4,0x8b,0x38,0x0a,0xac,0x72,0x21,0xd4,0xf8,0x07
// Game title
.byte 0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00,0x00
// Game code
.byte 0x00,0x00,0x00,0x00
// Maker code
.byte 0x00,0x00
// Fixed value
.byte 0x96
// Main unit code
.byte 0x00
// Device type (0x00 retail, 0x80 debug)
.byte 0x00
// Reserved
.byte 0x00,0x00,0x00,0x00,0x00,0x00,0x00
// Software version
.byte 0x00
// Complement check
.byte 0x51
// Reserved area
.space 98
targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
start_vector:
targets/gba: implement interrupt handler Thanks to Kyle Lemons for the inspiration and original design. The implementation in this commit is very different however, building on top of the software vectoring needed in RISC-V. The result is a flexible interrupt handler that does not take up any RAM for configuration.
5 years ago
// Configure stacks
targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
mov r0, #0x12 // Switch to IRQ Mode
msr cpsr, r0
targets/gba: make linker script cleaner Make it clearer where the stack is located. Additionally, get the heap to work (the GC needs to have _stack_top defined to work correctly).
5 years ago
ldr sp, =_stack_top_irq // Set IRQ stack
targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
mov r0, #0x1f // Switch to System Mode
msr cpsr, r0
targets/gba: make linker script cleaner Make it clearer where the stack is located. Additionally, get the heap to work (the GC needs to have _stack_top defined to work correctly).
5 years ago
ldr sp, =_stack_top // Set user stack
targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
targets/gba: implement interrupt handler Thanks to Kyle Lemons for the inspiration and original design. The implementation in this commit is very different however, building on top of the software vectoring needed in RISC-V. The result is a flexible interrupt handler that does not take up any RAM for configuration.
5 years ago
// Configure interrupt handler
mov r0, #0x4000000 // REG_BASE
ldr r1, =handleInterruptARM
str r1, [r0, #-4] // actually storing to 0x03007FFC due to mirroring
// Enable interrupts
mov r1, #1
str r1, [r0, #0x208] // 0x04000208 Interrupt Master Enable
targets: add support for GameBoy Advance Only tested in an emulator (mGBA). Almost nothing is supported, but drawing to the screen works.
5 years ago
// Jump to user code (switching to Thumb mode)
ldr r3, =main
bx r3
targets/gba: implement interrupt handler Thanks to Kyle Lemons for the inspiration and original design. The implementation in this commit is very different however, building on top of the software vectoring needed in RISC-V. The result is a flexible interrupt handler that does not take up any RAM for configuration.
5 years ago
// Small interrupt handler that immediately jumps to a function defined in the
// program (in Thumb) for further processing.
handleInterruptARM:
ldr r0, =handleInterrupt
bx r0