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