nero/rdos
1
0
Fork 0
Code Pull Requests Releases Activity

Clean up code for conditional jumps

Browse Source 
Amended: A binary file got in there
This commit is contained in:
Nero 2019-10-02 22:35:48 +00:00
parent 305663c110
commit 55db78a15d
1 changed files with 11 additions and 17 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

28
utils/emul.c
View File

@ -192,22 +192,6 @@ void modrm(int size) {
if (mod == 2) rmptr += (int16_t)imm16(); if (mod == 2) rmptr += (int16_t)imm16();
} }
int cond(int num) {
int r = 0;
switch(num >> 1) {
case 2:
r = !scratch;
break;
default:
fprintf(stderr, "Condition code %d not implemented\n", num);
exit(1);
break;
}
// Each odd condition is the negation of the previous
if (num & 1) r=1-r;
return r;
}
void push(uint16_t v) { void push(uint16_t v) {
SP -= 2; SP -= 2;
*(uint16_t*)&mem[SP] = v; *(uint16_t*)&mem[SP] = v;
@ -296,7 +280,17 @@ void step() {
break; break;
case 0x70 ... 0x7F: // Jcc case 0x70 ... 0x7F: // Jcc
reg = ip + (int8_t)imm8(); reg = ip + (int8_t)imm8();
if (cond(opcode-0x70)) { switch((opcode-0x70) >> 1) {
case 0: scratch = flags.bit.o; break;
case 1: scratch = flags.bit.s; break;
case 2: scratch = flags.bit.z; break;
case 3: scratch = flags.bit.c; break;
case 4: scratch = flags.bit.c || flags.bit.z; break;
case 5: scratch = flags.bit.s != flags.bit.o; break;
case 6: scratch = flags.bit.z || flags.bit.s != flags.bit.o; break;
case 7: scratch = flags.bit.p; break;
}
if (!!(opcode & 1) != scratch) {
ip = reg; ip = reg;
} }
break; break;