211 lines
7.0 KiB
C
211 lines
7.0 KiB
C
#include <stdio.h>
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/*
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Copyright (c) 2021 Devine Lu Linvega
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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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#include "uxn.h"
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Uxn cpu;
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#pragma mark - Helpers
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void
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setflag(Uint8 *status, char flag, int b)
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{
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if(b)
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*status |= flag;
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else
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*status &= (~flag);
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}
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int
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getflag(Uint8 *status, char flag)
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{
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return *status & flag;
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}
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#pragma mark - Operations
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/* clang-format off */
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Uint16 bytes2short(Uint8 a, Uint8 b) { return (a << 8) + b; }
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Uint16 mempeek16(Uxn *c, Uint16 s) { return (c->ram.dat[s] << 8) + (c->ram.dat[s+1] & 0xff); }
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void wspush8(Uxn *c, Uint8 b) { c->wst.dat[c->wst.ptr++] = b; }
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void wspush16(Uxn *c, Uint16 s) { wspush8(c,s >> 8); wspush8(c,s & 0xff); }
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Uint8 wspop8(Uxn *c) { return c->wst.dat[--c->wst.ptr]; }
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Uint16 wspop16(Uxn *c) { return wspop8(c) + (wspop8(c) << 8); }
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Uint8 wspeek8(Uxn *c, Uint8 o) { return c->wst.dat[c->wst.ptr - o]; }
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Uint16 wspeek16(Uxn *c, Uint8 o) { return bytes2short(c->wst.dat[c->wst.ptr - o], c->wst.dat[c->wst.ptr - o + 1]); }
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Uint16 rspop16(Uxn *c) { return c->rst.dat[--c->rst.ptr]; }
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void rspush16(Uxn *c, Uint16 a) { c->rst.dat[c->rst.ptr++] = a; }
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/* I/O */
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void op_brk(Uxn *c) { setflag(&c->status,FLAG_HALT, 1); }
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void op_lit(Uxn *c) { c->literal += c->ram.dat[c->ram.ptr++]; }
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void op_nop(Uxn *c) { (void)c; printf("NOP");}
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void op_ldr(Uxn *c) { wspush8(c, c->ram.dat[wspop16(c)]); }
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void op_str(Uxn *c) { c->ram.dat[wspop16(c)] = wspop8(c); }
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/* Logic */
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void op_jmp(Uxn *c) { c->ram.ptr = wspop16(c); }
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void op_jsr(Uxn *c) { rspush16(c, c->ram.ptr); c->ram.ptr = wspop16(c); }
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void op_rts(Uxn *c) { c->ram.ptr = rspop16(c); }
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/* Stack */
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void op_pop(Uxn *c) { wspop8(c); }
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void op_dup(Uxn *c) { wspush8(c,wspeek8(c,1)); }
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void op_swp(Uxn *c) { Uint8 b = wspop8(c), a = wspop8(c); wspush8(c,b); wspush8(c,a); }
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void op_ovr(Uxn *c) { Uint8 a = wspeek8(c,2); wspush8(c,a); }
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void op_rot(Uxn *c) { Uint8 c1 = wspop8(c),b = wspop8(c),a = wspop8(c); wspush8(c,b); wspush8(c, c1); wspush8(c,a); }
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void op_and(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,a & b); }
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void op_ora(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,a | b); }
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void op_rol(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,a << b); }
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/* Arithmetic */
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void op_add(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b + a); }
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void op_sub(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b - a); }
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void op_mul(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b * a); }
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void op_div(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b / a); }
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void op_equ(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b == a); }
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void op_neq(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b != a); }
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void op_gth(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b > a); }
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void op_lth(Uxn *c) { Uint8 a = wspop8(c), b = wspop8(c); wspush8(c,b < a); }
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/* Stack(16-bits) */
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void op_pop16(Uxn *c) { wspop16(c); }
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void op_dup16(Uxn *c) { wspush16(c,wspeek16(c,2)); }
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void op_swp16(Uxn *c) { Uint16 b = wspop16(c), a = wspop16(c); wspush16(c,b); wspush16(c,a); }
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void op_ovr16(Uxn *c) { Uint16 a = wspeek16(c, 4); wspush16(c,a); }
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void op_rot16(Uxn *c) { Uint16 c1 = wspop16(c), b = wspop16(c), a = wspop16(c); wspush16(c,b); wspush16(c, c1); wspush16(c,a); }
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void op_and16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,a & b); }
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void op_ora16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,a | b); }
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void op_rol16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,a << b); }
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/* Arithmetic(16-bits) */
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void op_add16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,b + a); }
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void op_sub16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,b - a); }
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void op_mul16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,b * a); }
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void op_div16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush16(c,b / a); }
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void op_equ16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush8(c,b == a); }
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void op_neq16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush8(c,b != a); }
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void op_gth16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush8(c,b > a); }
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void op_lth16(Uxn *c) { Uint16 a = wspop16(c), b = wspop16(c); wspush8(c,b < a); }
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void (*ops[])(Uxn *c) = {
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op_brk, op_lit, op_nop, op_nop, op_nop, op_nop, op_ldr, op_str,
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op_jmp, op_jsr, op_nop, op_rts, op_nop, op_nop, op_nop, op_nop,
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op_pop, op_dup, op_swp, op_ovr, op_rot, op_and, op_ora, op_rol,
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op_add, op_sub, op_mul, op_div, op_equ, op_neq, op_gth, op_lth,
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op_pop16, op_dup16, op_swp16, op_ovr16, op_rot16, op_and16, op_ora16, op_rol16,
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op_add16, op_sub16, op_mul16, op_div16, op_equ16, op_neq16, op_gth16, op_lth16
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};
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Uint8 opr[][2] = {
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{0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {2,1}, {3,0},
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{2,0}, {2,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0},
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{1,0}, {1,2}, {2,2}, {3,3}, {3,3}, {2,1}, {2,1}, {2,1},
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{2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1}, {2,1},
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{0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, /* TODO */
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{0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0}, {0,0} /* TODO */
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};
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/* clang-format on */
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int
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error(Uxn *c, char *name, int id)
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{
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printf("Error: %s#%04x, at 0x%04x\n", name, id, c->counter);
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return 0;
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}
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int
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doliteral(Uxn *c, Uint8 instr)
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{
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if(c->wst.ptr >= 255)
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return error(c, "Stack overflow", instr);
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wspush8(c, instr);
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c->literal--;
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return 1;
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}
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int
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dodevices(Uxn *c) /* experimental */
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{
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if(c->ram.dat[0xfff1]) {
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printf("%c", c->ram.dat[0xfff1]);
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c->ram.dat[0xfff1] = 0x00;
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}
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return 1;
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}
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int
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doopcode(Uxn *c, Uint8 instr)
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{
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Uint8 op = instr & 0x1f;
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setflag(&c->status, FLAG_SHORT, (instr >> 5) & 1);
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setflag(&c->status, FLAG_SIGN, (instr >> 6) & 1); /* usused */
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setflag(&c->status, FLAG_COND, (instr >> 7) & 1);
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if(getflag(&c->status, FLAG_SHORT))
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op += 16;
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if(c->wst.ptr < opr[op][0])
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return error(c, "Stack underflow", op);
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if(c->wst.ptr + opr[op][1] - opr[op][0] >= 255)
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return error(c, "Stack overflow", instr);
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if(!getflag(&c->status, FLAG_COND) || (getflag(&c->status, FLAG_COND) && wspop8(c)))
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(*ops[op])(c);
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dodevices(c);
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return 1;
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}
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int
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eval(Uxn *c)
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{
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Uint8 instr = c->ram.dat[c->ram.ptr++];
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if(c->literal > 0)
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return doliteral(c, instr);
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else
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return doopcode(c, instr);
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return 1;
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}
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int
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load(Uxn *c, char *filepath)
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{
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FILE *f;
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if(!(f = fopen(filepath, "rb")))
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return error(c, "Missing input.", 0);
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fread(c->ram.dat, sizeof(c->ram.dat), 1, f);
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return 1;
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}
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void
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reset(Uxn *c)
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{
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size_t i;
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char *cptr = (char *)c;
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for(i = 0; i < sizeof c; i++)
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cptr[i] = 0;
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}
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int
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boot(Uxn *c)
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{
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reset(c);
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c->vreset = mempeek16(c, 0xfffa);
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c->vframe = mempeek16(c, 0xfffc);
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c->verror = mempeek16(c, 0xfffe);
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/* eval reset */
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c->ram.ptr = c->vreset;
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setflag(&c->status, FLAG_HALT, 0);
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while(!(c->status & FLAG_HALT) && eval(c))
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c->counter++;
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/* eval frame */
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c->ram.ptr = c->vframe;
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setflag(&c->status, FLAG_HALT, 0);
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while(!(c->status & FLAG_HALT) && eval(c))
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c->counter++;
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return 1;
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}
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