6502
/
65816.js
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beginning of stack support with PHA and PLA

This commit is contained in:
Preston Skupinski 2011-05-08 22:20:33 -04:00
parent 86ea739777
commit 395e381c4f
1 changed files with 50 additions and 10 deletions
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60
cpu.js
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@ -17,15 +17,15 @@
function CPU_65816() {
// Registers
this.r = {
a:0, // Accumulator
b:0, // "Hidden" Accumulator Register(high byte in 8-bit mode)
x:0, // X Index Register
y:0, // Y Index Register
d:0, // Direct Page Register
s:0, // Stack Pointer
pc:0, // Program Counter
dbr:0, // Data Bank Register
pbr:0 // Program Bank Register
a:0, // Accumulator
b:0, // "Hidden" Accumulator Register(high byte in 8-bit mode)
x:0, // X Index Register
y:0, // Y Index Register
d:0, // Direct Page Register
s:0x1ff, // Stack Pointer
pc:0, // Program Counter
dbr:0, // Data Bank Register
pbr:0 // Program Bank Register
};
// P register flags.
@ -122,7 +122,8 @@ function CPU_65816() {
0x36 : ROL_direct_page_indexed_x, 0x6a : ROR_accumulator,
0x6e : ROR_absolute, 0x66 : ROR_direct_page,
0x7e : ROR_absolute_indexed_x,
0x76 : ROR_direct_page_indexed_x };
0x76 : ROR_direct_page_indexed_x,
0x48 : PHA , 0x68 : PLA };
/**
* Take a raw hex string representing the program and execute it.
@ -201,6 +202,45 @@ var MMU = {
}
};
var PHA = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m) {
cpu.mmu.store_byte(cpu.r.s--, cpu.r.a);
} else {
var low_byte = cpu.r.a & 0x00ff;
var high_byte = cpu.r.a >> 8;
cpu.mmu.store_byte(cpu.r.s--, high_byte);
cpu.mmu.store_byte(cpu.r.s--, low_byte);
}
}
};
var PLA = {
bytes_required:function() {
return 1;
},
execute:function(cpu) {
if(cpu.p.m) {
cpu.r.a = cpu.mmu.read_byte(++cpu.r.s);
cpu.p.n = cpu.r.a >> 7;
} else {
var low_byte = cpu.mmu.read_byte(++cpu.r.s);
var high_byte = cpu.mmu.read_byte(++cpu.r.s);
cpu.r.a = (high_byte<<8)|low_byte;
cpu.p.n = cpu.r.a >> 15;
}
if(cpu.r.a===0) {
cpu.p.z = 1;
} else {
cpu.p.z = 0;
}
}
};
var ROR_accumulator = {
bytes_required:function() {
return 1;