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void uPD96050::exec() {
uint24 opcode = programROM[regs.pc++];
switch(opcode >> 22) {
case 0: exec_op(opcode); break;
case 1: exec_rt(opcode); break;
case 2: exec_jp(opcode); break;
case 3: exec_ld(opcode); break;
}
int32 result = (int32)regs.k * regs.l; //sign + 30-bit result
regs.m = result >> 15; //store sign + top 15-bits
regs.n = result << 1; //store low 15-bits + zero
}
void uPD96050::exec_op(uint24 opcode) {
uint2 pselect = opcode >> 20; //P select
uint4 alu = opcode >> 16; //ALU operation mode
uint1 asl = opcode >> 15; //accumulator select
uint2 dpl = opcode >> 13; //DP low modify
uint4 dphm = opcode >> 9; //DP high XOR modify
uint1 rpdcr = opcode >> 8; //RP decrement
uint4 src = opcode >> 4; //move source
uint4 dst = opcode >> 0; //move destination
uint16 idb;
switch(src) {
case 0: idb = regs.trb; break;
case 1: idb = regs.a; break;
case 2: idb = regs.b; break;
case 3: idb = regs.tr; break;
case 4: idb = regs.dp; break;
case 5: idb = regs.rp; break;
case 6: idb = dataROM[regs.rp]; break;
case 7: idb = 0x8000 - regs.flaga.s1; break;
case 8: idb = regs.dr; regs.sr.rqm = 1; break;
case 9: idb = regs.dr; break;
case 10: idb = regs.sr; break;
case 11: idb = regs.si; break; //MSB
case 12: idb = regs.si; break; //LSB
case 13: idb = regs.k; break;
case 14: idb = regs.l; break;
case 15: idb = dataRAM[regs.dp]; break;
}
if(alu) {
uint16 p, q, r;
Flag flag;
bool c;
switch(pselect) {
case 0: p = dataRAM[regs.dp]; break;
case 1: p = idb; break;
case 2: p = regs.m; break;
case 3: p = regs.n; break;
}
switch(asl) {
case 0: q = regs.a; flag = regs.flaga; c = regs.flagb.c; break;
case 1: q = regs.b; flag = regs.flagb; c = regs.flaga.c; break;
}
switch(alu) {
case 1: r = q | p; break; //OR
case 2: r = q & p; break; //AND
case 3: r = q ^ p; break; //XOR
case 4: r = q - p; break; //SUB
case 5: r = q + p; break; //ADD
case 6: r = q - p - c; break; //SBB
case 7: r = q + p + c; break; //ADC
case 8: r = q - 1; p = 1; break; //DEC
case 9: r = q + 1; p = 1; break; //INC
case 10: r = ~q; break; //CMP
case 11: r = (q >> 1) | (q & 0x8000); break; //SHR1 (ASR)
case 12: r = (q << 1) | c; break; //SHL1 (ROL)
case 13: r = (q << 2) | 3; break; //SHL2
case 14: r = (q << 4) | 15; break; //SHL4
case 15: r = (q << 8) | (q >> 8); break; //XCHG
}
flag.s0 = (r & 0x8000);
flag.z = (r == 0);
switch(alu) {
case 1: case 2: case 3: case 10: case 13: case 14: case 15: {
flag.c = 0;
flag.ov0 = 0;
flag.ov1 = 0;
break;
}
case 4: case 5: case 6: case 7: case 8: case 9: {
if(alu & 1) {
//addition
flag.ov0 = (q ^ r) & ~(q ^ p) & 0x8000;
flag.c = (r < q);
} else {
//subtraction
flag.ov0 = (q ^ r) & (q ^ p) & 0x8000;
flag.c = (r > q);
}
if(flag.ov0) {
flag.s1 = flag.ov1 ^ !(r & 0x8000);
flag.ov1 = !flag.ov1;
}
break;
}
case 11: {
flag.c = q & 1;
flag.ov0 = 0;
flag.ov1 = 0;
break;
}
case 12: {
flag.c = q >> 15;
flag.ov0 = 0;
flag.ov1 = 0;
break;
}
}
switch(asl) {
case 0: regs.a = r; regs.flaga = flag; break;
case 1: regs.b = r; regs.flagb = flag; break;
}
}
exec_ld((idb << 6) + dst);
switch(dpl) {
case 1: regs.dp = (regs.dp & 0xf0) + ((regs.dp + 1) & 0x0f); break; //DPINC
case 2: regs.dp = (regs.dp & 0xf0) + ((regs.dp - 1) & 0x0f); break; //DPDEC
case 3: regs.dp = (regs.dp & 0xf0); break; //DPCLR
}
regs.dp ^= dphm << 4;
if(rpdcr) regs.rp--;
}
void uPD96050::exec_rt(uint24 opcode) {
exec_op(opcode);
regs.pc = regs.stack[--regs.sp];
}
void uPD96050::exec_jp(uint24 opcode) {
uint9 brch = opcode >> 13; //branch
uint11 na = opcode >> 2; //next address
uint2 bank = opcode >> 0; //bank address
uint14 jp = (regs.pc & 0x2000) | (bank << 11) | (na << 0);
switch(brch) {
case 0x000: regs.pc = regs.so; return; //JMPSO
case 0x080: if(regs.flaga.c == 0) regs.pc = jp; return; //JNCA
case 0x082: if(regs.flaga.c == 1) regs.pc = jp; return; //JCA
case 0x084: if(regs.flagb.c == 0) regs.pc = jp; return; //JNCB
case 0x086: if(regs.flagb.c == 1) regs.pc = jp; return; //JCB
case 0x088: if(regs.flaga.z == 0) regs.pc = jp; return; //JNZA
case 0x08a: if(regs.flaga.z == 1) regs.pc = jp; return; //JZA
case 0x08c: if(regs.flagb.z == 0) regs.pc = jp; return; //JNZB
case 0x08e: if(regs.flagb.z == 1) regs.pc = jp; return; //JZB
case 0x090: if(regs.flaga.ov0 == 0) regs.pc = jp; return; //JNOVA0
case 0x092: if(regs.flaga.ov0 == 1) regs.pc = jp; return; //JOVA0
case 0x094: if(regs.flagb.ov0 == 0) regs.pc = jp; return; //JNOVB0
case 0x096: if(regs.flagb.ov0 == 1) regs.pc = jp; return; //JOVB0
case 0x098: if(regs.flaga.ov1 == 0) regs.pc = jp; return; //JNOVA1
case 0x09a: if(regs.flaga.ov1 == 1) regs.pc = jp; return; //JOVA1
case 0x09c: if(regs.flagb.ov1 == 0) regs.pc = jp; return; //JNOVB1
case 0x09e: if(regs.flagb.ov1 == 1) regs.pc = jp; return; //JOVB1
case 0x0a0: if(regs.flaga.s0 == 0) regs.pc = jp; return; //JNSA0
case 0x0a2: if(regs.flaga.s0 == 1) regs.pc = jp; return; //JSA0
case 0x0a4: if(regs.flagb.s0 == 0) regs.pc = jp; return; //JNSB0
case 0x0a6: if(regs.flagb.s0 == 1) regs.pc = jp; return; //JSB0
case 0x0a8: if(regs.flaga.s1 == 0) regs.pc = jp; return; //JNSA1
case 0x0aa: if(regs.flaga.s1 == 1) regs.pc = jp; return; //JSA1
case 0x0ac: if(regs.flagb.s1 == 0) regs.pc = jp; return; //JNSB1
case 0x0ae: if(regs.flagb.s1 == 1) regs.pc = jp; return; //JSB1
case 0x0b0: if((regs.dp & 0x0f) == 0x00) regs.pc = jp; return; //JDPL0
case 0x0b1: if((regs.dp & 0x0f) != 0x00) regs.pc = jp; return; //JDPLN0
case 0x0b2: if((regs.dp & 0x0f) == 0x0f) regs.pc = jp; return; //JDPLF
case 0x0b3: if((regs.dp & 0x0f) != 0x0f) regs.pc = jp; return; //JDPLNF
case 0x0bc: if(regs.sr.rqm == 0) regs.pc = jp; return; //JNRQM
case 0x0be: if(regs.sr.rqm == 1) regs.pc = jp; return; //JRQM
case 0x100: regs.pc = jp & ~0x2000; return; //LJMP
case 0x101: regs.pc = jp | 0x2000; return; //HJMP
case 0x140: regs.stack[regs.sp++] = regs.pc; regs.pc = jp & ~0x2000; return; //LCALL
case 0x141: regs.stack[regs.sp++] = regs.pc; regs.pc = jp | 0x2000; return; //HCALL
}
}
void uPD96050::exec_ld(uint24 opcode) {
uint16 id = opcode >> 6; //immediate data
uint4 dst = opcode >> 0; //destination
switch(dst) {
case 0: break;
case 1: regs.a = id; break;
case 2: regs.b = id; break;
case 3: regs.tr = id; break;
case 4: regs.dp = id; break;
case 5: regs.rp = id; break;
case 6: regs.dr = id; regs.sr.rqm = 1; break;
case 7: regs.sr = (regs.sr & 0x907c) | (id & ~0x907c); break;
case 8: regs.so = id; break; //LSB
case 9: regs.so = id; break; //MSB
case 10: regs.k = id; break;
case 11: regs.k = id; regs.l = dataROM[regs.rp]; break;
case 12: regs.l = id; regs.k = dataRAM[regs.dp | 0x40]; break;
case 13: regs.l = id; break;
case 14: regs.trb = id; break;
case 15: dataRAM[regs.dp] = id; break;
}
}
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