diff options
| author | vin <git@vineetk.net> | 2024-06-17 15:11:45 +0530 |
|---|---|---|
| committer | vin <git@vineetk.net> | 2024-06-17 15:11:45 +0530 |
| commit | 6a5b0b728e522cd4e90a2ae775666ad6c36d3c5a (patch) | |
| tree | 5c00833ff654217b4d7c73b9e4dfe93ad4f9ee02 /cpu.c | |
| parent | 77d37dd455f804c79969979eb39d525b3c5ddfe7 (diff) | |
start fixing bugs with memory access
So this is why tests should be written while writing the program
and instructions instead of all at once later. If this were all to be
rewritten (which it probably will), I should add tests for each opcode
instead of waiting until the end for ROM loading support.
Diffstat (limited to 'cpu.c')
| -rw-r--r-- | cpu.c | 20 |
1 files changed, 10 insertions, 10 deletions
@@ -81,10 +81,8 @@ peek(uint16_t addr) static uint16_t peek16(uint16_t addr) { - MEMORY_MIRROR(addr); - /* bytes are stored in little-endian (low then high) */ - return (uint16_t)memory[addr] | ((uint16_t)memory[addr + 1] << 8); + return peek(addr) | (peek(addr + 1) << 8); } static void @@ -108,7 +106,7 @@ memwrite16(uint16_t addr, uint16_t word) static uint8_t opcode_arg(enum addressing_mode mode) { - uint8_t arg, val; + uint16_t arg, val; if (mode != AM_ABS && mode != AM_ABS_X && mode != AM_ABS_Y) arg = peek(regs.pc++); @@ -149,14 +147,15 @@ opcode_arg(enum addressing_mode mode) abort(); } + printf("arg: $%04X $%04X\n", arg, val); + return val; } static uint16_t opcode_mem(enum addressing_mode mode) { - uint8_t arg; - uint16_t val; + uint16_t arg, val; if (mode != AM_ABS && mode != AM_ABS_X && mode != AM_ABS_Y) arg = peek(regs.pc++); @@ -173,6 +172,7 @@ opcode_mem(enum addressing_mode mode) case AM_ZP_Y: val = (arg + regs.y) % 256; break; + case AM_IMM: case AM_ABS: val = arg; break; @@ -1059,7 +1059,7 @@ interpret(void) cycles += 2; break; case 0x4c: - jmp(opcode_arg(AM_ABS)); + jmp(opcode_mem(AM_ABS)); cycles += 3; break; case 0x6c: @@ -1111,7 +1111,7 @@ interpret(void) cycles += 5; break; case 0xa2: - ldx(opcode_arg(AM_IMM)); + ldx(opcode_mem(AM_IMM)); cycles += 2; break; case 0xa6: @@ -1467,8 +1467,8 @@ main(int argc, char *argv[]) return 1; } - memwrite16(0xFFFC, 0x8000); - regs.pc = 0x8000; + memwrite16(0xFFFC, 0xC000); + regs.pc = 0xC000; printf("status: %i%i%i%i%i%i%i%i\n", regs.status.carry, regs.status.zero, regs.status.interrupt_disable, |