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mwillsey · Feb 8, 2014 · a5d86e3 · a5d86e3
1 parent 9ebaf90
commit a5d86e3
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Showing 2 changed files with 10 additions and 3 deletions.
diff --git a/6502.c b/6502.c
@@ -551,7 +551,9 @@ void ROR (cpu *c, addr a) {
 
 /* jump to another location */
 void JMP (cpu *c, addr a) {
-  c->PC = mem_read(c->mem, a);
+  byte b = mem_read(c->mem, a);
+  printf("jumping to %04x\n", b);
+  c->PC = b;
 }
 
 /* jump to subroutine */
@@ -717,6 +719,10 @@ void cpu_init (cpu *c, memory *mem) {
   set_flag(c, 5, 1);
   /* set stack pointer */
   c->SP = 0xfd;
+  /* clear registers */
+  c->A = 0;
+  c->X = 0;
+  c->Y = 0;
   /* load program counter to address at 0xfffc/d*/
   c->PC = ((addr)(mem_read(c->mem, 0xfffd)) << 8) | mem_read(c->mem, 0xfffc);
 }

diff --git a/nes.c b/nes.c
@@ -33,10 +33,11 @@ int main (int argc, char** argv) {
   /*   fread(nes_cpu.cartidge_lower_bank, sizeof(byte), in_stat.st_size, in); */
 
   /* for the nestest rom */
-  fread(mem.arr+0x8000-16, sizeof(byte), 0x4000, in);
+  fread(mem.arr+0xc000-16, sizeof(byte), 0x4000, in);
   nes_cpu.PC = 0xc000;
 
-  for(int i = 0; i < 10000; i++) {
+  int i;
+  for(i = 0; i < 10000; i++) {
     cpu_step(&nes_cpu);
   }