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Advance PC by # of bytes consumed

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This commit is contained in:
Peter Evans 2018-01-05 15:52:20 -06:00
parent 7ceee608b3
commit af7dae6924
1 changed files with 14 additions and 1 deletions
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15
src/mos6502.c
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@ -13,6 +13,7 @@
#include "log.h"
#include "mos6502.h"
#include "mos6502.dis.h"
// All of our address modes, instructions, etc. are defined here.
#include "mos6502.enums.h"
@ -353,10 +354,19 @@ void
mos6502_execute(mos6502 *cpu, vm_8bit opcode)
{
vm_8bit operand = 0;
int cycles;
int cycles, bytes;
mos6502_address_resolver resolver;
mos6502_instruction_handler handler;
// We want to know how many bytes this opcode and its operand
// consume. We know the opcode is one byte.
bytes = 1;
// The disassembler knows how many bytes each operand requires
// (maybe this code doesn't belong in the disassembler); let's use
// that to figure out the total number of bytes to skip.
bytes += mos6502_dis_expected_bytes(mos6502_addr_mode(opcode));
// First, we need to know how to resolve our effective address and
// how to execute anything.
resolver = mos6502_get_address_resolver(opcode);
@ -393,6 +403,9 @@ mos6502_execute(mos6502 *cpu, vm_8bit opcode)
// something.
usleep(cycles * 100000);
// Update the counter to move beyond the opcode and its operand.
cpu->PC += bytes;
// Ok -- we're done! This wasn't so hard, was it?
return;
}