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135 lines
3.0 KiB
C
135 lines
3.0 KiB
C
/************************************
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* C02 Conditional Parsing Routines *
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************************************/
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#include <stdio.h>
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#include <stdlib.h>
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#include <ctype.h>
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#include <string.h>
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#include <errno.h>
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#include "common.h"
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#include "asm.h"
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#include "parse.h"
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#include "vars.h"
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#include "expr.h"
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#include "label.h"
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#include "cond.h"
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int cmprtr; //Encoded Comparison Operator
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int cmpenc; //Encoded Comparator Character
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/* Convert Comparison Operator Character *
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* Args: Comparison Operator Character *
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* Returns: Comparison Operator Bit Mask */
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int enccmp(char c)
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{
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int e;
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switch(c)
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{
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case '=': e = 1; break;
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case '<': e = 2; break;
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case '>': e = 4; break;
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default: e = 0;
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}
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if (e) {
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CCMNT(c);
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skpchr();
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}
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return e;
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}
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/* Process and Compile Comparison Operator and *
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* Args: comparator - Encoded Comparison Operator *
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* Uses: term - Term Being Compared Against *
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* label - Branch Target if Comparison is FALSE */
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void prccmp(int cmprtr)
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{
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DEBUG("Processing comparison operator %d\n", cmprtr);
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switch(cmprtr) {
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case 1: // = or ==
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asmlin("CMP", term);
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asmlin("BNE", curlbl);
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break;
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case 2: // <
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if (cmpsgn) {
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asmlin("CMP", term);
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asmlin("BPL", curlbl);
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}
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else {
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asmlin("CMP", term);
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asmlin("BCS", curlbl);
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}
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break;
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case 3: // <= or =<
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if (cmpsgn) {
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asmlin("CMP", term);
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asmlin("BPL", curlbl);
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asmlin("BNE", curlbl);
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}
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else {
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asmlin("CLC", "");
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asmlin("SBC", term);
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asmlin("BCS", curlbl);
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}
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break;
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case 4: // >
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if (cmpsgn) {
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asmlin("CMP", term);
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asmlin("BMI", curlbl);
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asmlin("BEQ", curlbl);
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}
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else {
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asmlin("CLC", "");
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asmlin("SBC", term);
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asmlin("BCC", curlbl);
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}
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break;
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case 5: // >= or =>
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if (cmpsgn) {
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asmlin("CMP", term);
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asmlin("BMI", curlbl);
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}
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else {
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asmlin("CMP", term);
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asmlin("BCC", curlbl);
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}
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break;
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case 6: // <> or ><
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asmlin("CMP", term);
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asmlin("BEQ", curlbl);
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break;
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default:
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printf("Unsupported comparison operator index %d\n", cmprtr);
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exterr(EXIT_FAILURE);
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}
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}
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/* Parse Comparison Operator *
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* Sets: comparitor - Encoded Comparison Operator */
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int prscmp()
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{
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cmpenc = enccmp(nxtchr); //Encode Comparison Character
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if (cmpenc == 0)
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expctd("comparison operator");
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cmprtr = cmpenc; //Set Encoded Comparator
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cmpenc = enccmp(nxtchr); //Encode Next Comparison Character
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if (cmpenc != 0)
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cmprtr = cmprtr | cmpenc; //Combine Encoded Comparator
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skpspc();
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DEBUG("Parsed comparator %d\n", cmprtr);
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}
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/* Parse and Compile Conditional Expression *
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* Condition = <expression> <comparator> <term> */
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void prscnd(char trmntr)
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{
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DEBUG("Parsing condition\n", 0);
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prsxpr(0);
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skpspc();
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prscmp();
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prstrm();
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CCMNT(trmntr);
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prccmp(cmprtr);
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expect(trmntr);
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}
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