301 lines
5.1 KiB
C
301 lines
5.1 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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typedef unsigned char Uint8;
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typedef unsigned short Uint16;
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typedef struct {
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int ptr;
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Uint8 data[65536];
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} Program;
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typedef struct {
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Uint16 addr;
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char name[64];
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} Label;
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int labelslen;
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Label labels[256];
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/* clang-format off */
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char opcodes[][4] = {
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"BRK", "RTS", "LIT", "POP", "DUP", "SWP", "OVR", "ROT",
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"JMU", "JSU", "JMC", "JSC", "EQU", "NEQ", "GTH", "LTH",
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"AND", "ORA", "ROL", "ROR", "ADD", "SUB", "MUL", "DIV",
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"LDR", "STR", "---", "---", "---", "---", "---", "---"
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};
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/* clang-format on */
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Program p;
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#pragma mark - Helpers
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int
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scmp(char *a, char *b) /* string compare */
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{
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int i = 0;
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while(a[i] == b[i])
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if(!a[i++])
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return 1;
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return 0;
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}
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char *
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scpy(char *src, char *dst, int len) /* string copy */
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{
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int i = 0;
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while((dst[i] = src[i]) && i < len - 2)
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i++;
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dst[i + 1] = '\0';
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return dst;
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}
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int
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slen(char *s) /* string length */
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{
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int i = 0;
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while(s[i] && s[++i])
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;
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return i;
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}
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char *
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suca(char *s) /* string to uppercase */
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{
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int i = 0;
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char c;
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while((c = s[i]))
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s[i++] = c >= 'a' && c <= 'z' ? c - ('a' - 'A') : c;
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return s;
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}
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int
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sihx(char *s) /* string is hexadecimal */
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{
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int i = 0;
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char c;
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while((c = s[i++]))
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if(!(c >= '0' && c <= '9') && !(c >= 'a' && c <= 'f') && !(c >= 'A' && c <= 'F'))
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return 0;
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return 1;
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}
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int
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shex(char *s) /* string to num */
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{
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int n = 0, i = 0;
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char c;
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while((c = s[i++]))
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if(c >= '0' && c <= '9')
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n = n * 16 + (c - '0');
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else if(c >= 'A' && c <= 'F')
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n = n * 16 + 10 + (c - 'A');
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else if(c >= 'a' && c <= 'f')
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n = n * 16 + 10 + (c - 'a');
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return n;
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}
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int
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ismarker(char *w)
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{
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return w[0] == '[' || w[0] == ']' || w[0] == '{' || w[0] == '}';
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}
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int
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iscomment(char *w, int *skip)
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{
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if(w[0] == ')') {
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*skip = 0;
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return 1;
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}
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if(w[0] == '(') *skip = 1;
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if(*skip) return 1;
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return 0;
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}
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#pragma mark - I/O
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void
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pushbyte(Uint8 b, int lit)
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{
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if(lit) {
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pushbyte(0x02, 0);
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pushbyte(0x01, 0);
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}
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p.data[p.ptr++] = b;
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}
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void
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pushshort(Uint16 s, int lit)
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{
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if(lit) {
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pushbyte(0x02, 0);
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pushbyte(0x02, 0);
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}
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pushbyte((s >> 8) & 0xff, 0);
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pushbyte(s & 0xff, 0);
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}
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void
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pushword(char *w)
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{
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int i = slen(w);
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pushbyte(0x02, 0);
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pushbyte(slen(w), 0);
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while(i > 0)
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pushbyte(w[--i], 0);
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}
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Label *
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findlabel(char *s)
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{
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int i;
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for(i = 0; i < labelslen; ++i)
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if(scmp(labels[i].name, s))
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return &labels[i];
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return NULL;
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}
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#pragma mark - Parser
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int
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error(char *name, char *id)
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{
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printf("Error: %s(%s)\n", name, id);
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return 0;
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}
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Uint8
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findop(char *s)
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{
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int i;
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for(i = 0; i < 32; ++i)
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if(scmp(opcodes[i], s))
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return i;
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return 0;
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}
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int
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makelabel(char *id, Uint16 addr)
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{
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Label *l;
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if(findlabel(id))
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return error("Label duplicate", id);
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l = &labels[labelslen++];
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scpy(id, l->name, 64);
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l->addr = addr;
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printf("New label: %s[0x%02x]\n", l->name, l->addr);
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return 1;
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}
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int
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makeconst(char *id, FILE *f)
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{
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char wv[64];
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fscanf(f, "%s", wv);
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return makelabel(id, shex(wv));
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}
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int
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pass1(FILE *f)
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{
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int skip = 0, vars = 0;
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Uint16 addr = 0;
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char w[64];
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while(fscanf(f, "%s", w) == 1) {
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if(iscomment(w, &skip)) continue;
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suca(w);
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if(w[0] == '@' && !makelabel(w + 1, addr))
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return error("Pass1 failed", w);
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if(w[0] == ';' && !makelabel(w + 1, vars++))
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return error("Pass1 failed", w);
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if(w[0] == ':') {
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if(!makeconst(w + 1, f))
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return error("Pass1 failed", w);
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else
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continue;
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}
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/* move addr ptr */
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if(findop(w) || scmp(w, "BRK"))
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addr += 1;
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else if(w[0] == '|')
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addr = shex(w + 1);
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else if(w[0] == '@')
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addr += 0;
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else if(w[0] == ';')
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addr += 0;
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else if(w[0] == '.')
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addr += 2;
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else if(w[0] == '"')
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addr += slen(w + 1) + 2;
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else if(w[0] == ',')
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addr += 4;
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else if(ismarker(w))
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addr += 0;
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else
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return error("Unknown label", w);
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}
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rewind(f);
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return 1;
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}
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int
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pass2(FILE *f)
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{
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int skip = 0;
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char w[64];
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while(fscanf(f, "%s", w) == 1) {
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Uint8 op = 0;
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Label *l;
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if(w[0] == '@') continue;
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if(w[0] == ';') continue;
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suca(w);
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if(iscomment(w, &skip) || ismarker(w)) continue;
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if(w[0] == '|')
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p.ptr = shex(w + 1);
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else if(w[0] == ':')
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fscanf(f, "%s", w);
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else if(w[0] == '"')
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pushword(w + 1);
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else if((op = findop(w)) || scmp(w, "BRK"))
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pushbyte(op, 0);
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else if((l = findlabel(w + 1)))
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pushshort(l->addr, w[0] == ',');
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else if(sihx(w + 1) && slen(w + 1) == 2)
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pushbyte(shex(w + 1), w[0] == ',');
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else if(sihx(w + 1) && slen(w + 1) == 4)
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pushshort(shex(w + 1), w[0] == ',');
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else
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return error("Unknown label", w);
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}
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return 1;
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}
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int
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main(int argc, char *argv[])
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{
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FILE *f;
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if(argc < 3)
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return error("Input", "Missing");
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if(!(f = fopen(argv[1], "r")))
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return error("Open", "Failed");
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if(!pass1(f) || !pass2(f))
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return error("Assembly", "Failed");
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fwrite(p.data, sizeof(p.data), 1, fopen(argv[2], "wb"));
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fclose(f);
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printf("Assembled %s.\n", argv[2]);
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return 0;
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}
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