6502/65816.js
1
0
Fork 0
mirror of https://github.com/pskupinski/65816.js.git synced 2024-06-05 22:29:30 +00:00
Code Issues Projects Releases Wiki Activity

added JMP absolute indirect and repositioned the incrementing of the program counter so the program counter doesn't incorrectly increment after a branch or jump and increments at the correct time anyways

Browse Source
This commit is contained in:
Preston Skupinski 2011-05-02 18:10:17 -04:00
parent 952b6ba840
commit 8a401c9eba
1 changed files with 18 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

21
cpu.js
View File

@ -43,6 +43,7 @@ function CPU_65816() {
this.mmu = MMU;
this.mmu.cpu = this;
var inc_pc = true;
this.opcode_map = { 0xfb : XCE, 0x18 : CLC, 0x78 : SEI, 0x38 : SEC,
0x58 : CLI, 0xc2 : REP, 0xe2 : SEP,
@ -74,7 +75,8 @@ function CPU_65816() {
0x9e : STZ_absolute_indexed_x,
0x74 : STZ_direct_page_indexed_x, 0x9b : TXY,
0xbb : TYX, 0xaa : TAX, 0xa8 : TAY, 0x8a : TXA,
0x98 : TYA, 0x4c : JMP_absolute };
0x98 : TYA, 0x4c : JMP_absolute,
0x6c : JMP_absolute_indirect };
}
var MMU = {
@ -114,6 +116,18 @@ var MMU = {
}
};
var JMP_absolute_indirect = {
bytes_required:function() {
return 3;
},
execute:function(cpu, bytes) {
var location = (bytes[1]<<8)|bytes[0];
var low_byte = cpu.mmu.read_byte(location);
var high_byte = cpu.mmu.read_byte(location+1);
cpu.r.pc = high_byte | low_byte;
}
};
var JMP_absolute = {
bytes_required:function() {
return 3;
@ -1205,6 +1219,8 @@ CPU_65816.prototype.execute = function(raw_hex, has_header) {
var executing = true;
while(executing) {
var b = this.mmu.read_byte(this.r.pc);
this.r.pc++;
// If we reach the end of the code then stop everything.
if(b==null) {
break;
@ -1220,11 +1236,10 @@ CPU_65816.prototype.execute = function(raw_hex, has_header) {
} else {
var bytes = [];
for(var i = 1; i < bytes_required; i++) {
this.r.pc++;
bytes.push(this.mmu.read_byte(this.r.pc));
this.r.pc++;
}
operation.execute(this,bytes);
}
this.r.pc++;
}
}