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Z80.js
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Z80.js
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const { MMU } = require('./MMU');
Z80 = {
// Time clock: The Z80 holds two types of clock (m and t)
_clock = { m : 0, t: 0 },
_r: {
a: 0,
b: 0,
c: 0,
d: 0,
e: 0,
f: 0,
h: 0,
l: 0,
pc: 0,
sp: 0,
m: 0,
t: 0
},
// Add E to A, leaving result in A (ADD A, E)
ADDr_e = () => {
Z80._r.a += Z80._r.e;
Z80._r.f = 0;
if (!Z80._r.a) Z80._r.f |= 0x80;
if (Z80._r.a > 255) Z80._r.f |= 0x10;
Z80._r.a &= 255;
Z80._r.m = 1;
Z80._r.t = 4;
},
// Add B to A, setting the flags CP (A, B)
CPr_b = () => {
const i = Z80._r.a;
i -= Z80._r.b;
Z80._r.f |= 0x40;
if (i === 0) Z80._r.f |= 0x80;
if (i < 0) Z80._r.f |= 0x10;
Z80._r.m = 1;
Z80._r.t = 4;
},
// Don't perfome any operation
NOP = () => {
Z80._r.m = 1;
Z80._r.t = 4;
},
PUSHBC = () => {
Z80._r.sp--;
MMU.wb(Z80._r.sp, Z80._r.b);
Z80._r.sp--;
MMU.wb(Z80._r.sp, Z80._r.c);
Z80._r.m = 3;
Z80._r.t = 12
},
POPHL = () => {
Z80._r.l = MMU.rb(Z80._r.sp);
Z80._r.sp++;
Z80._r.h = MMU.rb(Z80._r.sp);
Z80._r.sp++;
Z80._r.m = 3;
Z80._r.t = 12
},
LDAmm = () => {
const address = MMU.rw(Z80._r.pc);
Z80._r.pc += 2;
Z80._r.a = MMU.rb(address);
Z80._r.m = 4;
Z80._r.t = 16
},
reset = () => {
Z80._r.a = 0;
Z80._r.b = 0;
Z80._r.c = 0;
Z80._r.d = 0;
Z80._r.e = 0;
Z80._r.h = 0;
Z80._r.l = 0;
Z80._r.f = 0;
Z80._r.sp = 0;
Z80._r.pc = 0;
Z80._clock.m = 0;
Z80._clock.t = 0;
}
}