mirror of https://git.sr.ht/~rabbits/uxn
88 lines
3.8 KiB
C
88 lines
3.8 KiB
C
#include "uxn.h"
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/*
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Copyright (u) 2022-2023 Devine Lu Linvega, Andrew Alderwick, Andrew Richards
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Permission to use, copy, modify, and distribute this software for any
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purpose with or without fee is hereby granted, provided that the above
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copyright notice and this permission notice appear in all copies.
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THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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WITH REGARD TO THIS SOFTWARE.
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*/
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#define FLIP { s = ins & 0x40 ? &u->wst : &u->rst; }
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#define JUMP(x) { if(m2) pc = (x); else pc += (Sint8)(x); }
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#define POKE(x, y) { if(m2) { POKE2(ram + x, y) } else ram[(x)] = (y); }
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#define PEEK(o, x) { if(m2) { o = PEEK2(ram + x); } else o = ram[(x)]; }
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#define DEVR(o, p) { if(m2) { o = ((emu_dei(u, p) << 8) + emu_dei(u, p + 1)); } else o = emu_dei(u, p); }
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#define DEVW(p, y) { if(m2) { emu_deo(u, p, y >> 8); emu_deo(u, p + 1, y); } else emu_deo(u, p, y); }
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#define PUSH1(y) { s->dat[s->ptr++] = (y); }
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#define PUSH2(y) { t = (y); s->dat[s->ptr++] = t >> 0x8; s->dat[s->ptr++] = t & 0xff; }
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#define PUSHx(y) { if(m2) { PUSH2(y) } else PUSH1(y) }
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#define POP1(o) { o = s->dat[--*sp]; }
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#define POP2(o) { o = s->dat[--*sp] | s->dat[--*sp] << 0x8; }
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#define POPx(o) { if(m2) { POP2(o) } else POP1(o) }
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int
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uxn_eval(Uxn *u, Uint16 pc)
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{
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Uint8 ksp, *sp, *ram = u->ram;
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Uint16 a, b, c, t;
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if(!pc || u->dev[0x0f]) return 0;
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for(;;) {
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Uint8 ins = ram[pc++], opc = ins & 0x1f;
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Uint8 m2 = ins & 0x20;
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Stack *s = ins & 0x40 ? &u->rst : &u->wst;
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if(ins & 0x80) {
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ksp = s->ptr;
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sp = &ksp;
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} else
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sp = &s->ptr;
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/* Opcodes */
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switch(opc - (!opc * (ins >> 5))) {
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/* Immediate */
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case -0x0: /* BRK */ return 1;
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case -0x1: /* JCI */ POP1(b) if(!b) { pc += 2; break; } /* else fallthrough */
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case -0x2: /* JMI */ pc += PEEK2(ram + pc) + 2; break;
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case -0x3: /* JSI */ PUSH2(pc + 2) pc += PEEK2(ram + pc) + 2; break;
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case -0x4: /* LIT */
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case -0x6: /* LITr */ PUSH1(ram[pc++]) break;
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case -0x5: /* LIT2 */
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case -0x7: /* LIT2r */ PUSH2(PEEK2(ram + pc)) pc += 2; break;
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/* ALU */
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case 0x01: /* INC */ POPx(a) PUSHx(a + 1) break;
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case 0x02: /* POP */ POPx(a) break;
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case 0x03: /* NIP */ POPx(a) POPx(b) PUSHx(a) break;
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case 0x04: /* SWP */ POPx(a) POPx(b) PUSHx(a) PUSHx(b) break;
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case 0x05: /* ROT */ POPx(a) POPx(b) POPx(c) PUSHx(b) PUSHx(a) PUSHx(c) break;
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case 0x06: /* DUP */ POPx(a) PUSHx(a) PUSHx(a) break;
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case 0x07: /* OVR */ POPx(a) POPx(b) PUSHx(b) PUSHx(a) PUSHx(b) break;
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case 0x08: /* EQU */ POPx(a) POPx(b) PUSH1(b == a) break;
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case 0x09: /* NEQ */ POPx(a) POPx(b) PUSH1(b != a) break;
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case 0x0a: /* GTH */ POPx(a) POPx(b) PUSH1(b > a) break;
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case 0x0b: /* LTH */ POPx(a) POPx(b) PUSH1(b < a) break;
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case 0x0c: /* JMP */ POPx(a) JUMP(a) break;
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case 0x0d: /* JCN */ POPx(a) POP1(b) if(b) JUMP(a) break;
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case 0x0e: /* JSR */ POPx(a) FLIP PUSH2(pc) JUMP(a) break;
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case 0x0f: /* STH */ POPx(a) FLIP PUSHx(a) break;
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case 0x10: /* LDZ */ POP1(a) PEEK(b, a) PUSHx(b) break;
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case 0x11: /* STZ */ POP1(a) POPx(b) POKE(a, b) break;
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case 0x12: /* LDR */ POP1(a) PEEK(b, pc + (Sint8)a) PUSHx(b) break;
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case 0x13: /* STR */ POP1(a) POPx(b) POKE(pc + (Sint8)a, b) break;
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case 0x14: /* LDA */ POP2(a) PEEK(b, a) PUSHx(b) break;
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case 0x15: /* STA */ POP2(a) POPx(b) POKE(a, b) break;
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case 0x16: /* DEI */ POP1(a) DEVR(b, a) PUSHx(b) break;
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case 0x17: /* DEO */ POP1(a) POPx(b) DEVW(a, b) break;
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case 0x18: /* ADD */ POPx(a) POPx(b) PUSHx(b + a) break;
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case 0x19: /* SUB */ POPx(a) POPx(b) PUSHx(b - a) break;
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case 0x1a: /* MUL */ POPx(a) POPx(b) PUSHx((Uint32)b * a) break;
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case 0x1b: /* DIV */ POPx(a) POPx(b) PUSHx(a ? b / a : 0) break;
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case 0x1c: /* AND */ POPx(a) POPx(b) PUSHx(b & a) break;
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case 0x1d: /* ORA */ POPx(a) POPx(b) PUSHx(b | a) break;
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case 0x1e: /* EOR */ POPx(a) POPx(b) PUSHx(b ^ a) break;
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case 0x1f: /* SFT */ POP1(a) POPx(b) PUSHx(b >> (a & 0xf) << (a >> 4)) break;
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}
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}
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}
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