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347 lines
9.2 KiB
Plaintext
347 lines
9.2 KiB
Plaintext
1File: CEXPR.C Page 1
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1 /*
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2 Copyright 1982
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3 Alcyon Corporation
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4 8716 Production Ave.
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5 San Diego, Ca. 92121
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6 */
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7
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8 #include "preproc.h"
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9
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10 #define OPPRI 077
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11 #define OPBIN 0100
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12 #define STKLEN 64
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13 int oprstk[STKLEN]; /*operator stack*/
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14 int opnstk[STKLEN]; /*operand stack*/
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15 int pristk[STKLEN]; /*operator priority stack*/
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16 int *oprptr; /*pointer to operator stack*/
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17 int *opnptr; /*pointer to operand stack*/
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18 int *priptr; /*pointer to priority stack*/
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19 int cvalue;
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20
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21 int opinfo[] {
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22 0, /*EOF=0*/
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23 16|OPBIN, /*SUB=1*/
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24 16|OPBIN, /*ADD=2*/
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25 20, /*NOT=3*/
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26 20, /*NEG=4*/
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27 22, /*LPAREN=5*/
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28 2, /*RPAREN=6*/
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29 6|OPBIN, /*QMARK=7*/
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30 6|OPBIN, /*COLON=8*/
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31 8|OPBIN, /*OR=9*/
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32 10|OPBIN, /*AND=10*/
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33 8|OPBIN, /*XOR=11*/
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34 12|OPBIN, /*EQUAL=12*/
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35 12|OPBIN, /*NEQUAL=13*/
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36 14|OPBIN, /*LESS=14*/
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37 14|OPBIN, /*LSEQUAL=15*/
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38 14|OPBIN, /*GREAT=16*/
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39 14|OPBIN, /*GREQUAL=17*/
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40 4|OPBIN, /*LSHIFT=18*/
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41 4|OPBIN, /*RSHIFT=19*/
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42 18|OPBIN, /*MULT=20*/
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43 18|OPBIN, /*DIV=21*/
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44 18|OPBIN, /*MOD=22*/
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45 20, /*COMPL=23*/
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46 };
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47
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48 /* cexpr - constant expression evaluation*/
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49 /* Does priority-driven operator/operand stack evaluation of*/
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50 /* constant expressions.*/
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51 cexpr() /* returns constant evaluated*/
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52 {
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53 register int lop, type;
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54
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55 oprptr = &oprstk[0];
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56 opnptr = &opnstk[0];
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57 priptr = &pristk[0];
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58 *priptr = 0;
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59 lop = -1;
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1File: CEXPR.C Page 2
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60 while(1) {
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61 switch( type = getctok() ) {
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62
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63 case CONST:
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64 if( !lop ) /*last was not operator*/
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65 goto syntax;
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66 if( opnptr >= &opnstk[STKLEN] ) {
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67 error("expression stack overflow");
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68 cexit();
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69 }
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70 lop = FALSE;
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71 *++opnptr = cvalue;
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72 continue;
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73
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74 case SUB:
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75 if( lop )
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76 type = NEG; /*unary minus*/
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77 break;
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78
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79 case ADD:
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80 if( lop )
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81 continue; /*ignore unary +*/
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82 break;
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83
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84 case COMPL:
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85 case LPAREN:
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86 case NOT:
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87 if( !lop )
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88 goto syntax;
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89 break;
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90
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91 case RPAREN:
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92 if( lop )
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93 goto syntax;
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94 lop = FALSE;
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95 if( !stkop(type) )
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96 goto syntax;
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97 continue;
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98
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99 case NEWL:
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100 case EOF:
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101 if( lop || !stkop(EOF) || opnptr != &opnstk[1] )
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102 goto syntax;
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103 type = opnstk[1];
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104 putback('\n');
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105 return(type);
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106
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107 default:
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108 if( lop || type > LASTOP )
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109 goto syntax;
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110 break;
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111 }
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112 lop = TRUE;
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113 if( !stkop(type) )
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114 goto syntax;
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115 }
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116 syntax:
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117 error("expression syntax");
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118 if( type == NEWL )
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1File: CEXPR.C Page 3
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119 putback('\n');
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120 return(0);
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121 }
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122
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123 /* getctok - get a constant expression token*/
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124 /* Handles conversion of quoted character strings and numbers.*/
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125 getctok()
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126 {
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127 register int type, c, count;
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128 register char *p;
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129 char token[TOKSIZE];
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130
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131 while( 1 ) {
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132 switch( type = getntok(token) ) {
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133
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134 case DIGIT:
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135 cvalue = const(token);
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136 return(CONST);
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137
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138 case SQUOTE:
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139 for( cvalue = 0, p = &token[1], count = 2; --count >= 0; ) {
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140 if( (c= *p++) == '\'' )
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141 break;
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142 if( c == '\\' ) {
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143 if( *p >= '0' && *p <= '7' ) {
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144 for( c = 0; *p >= '0' && *p <= '7'; )
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145 c = (c<<3) + (*p++ - '0');
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146 }
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147 else switch( c = *p++ ) {
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148
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149 case 'n':
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150 c = '\n';
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151 break;
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152
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153 case 't':
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154 c = '\t';
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155 break;
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156
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157 case 'b':
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158 c = '\b';
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159 break;
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160
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161 case 'r':
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162 c = '\r';
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163 break;
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164
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165 case 'f':
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166 c = '\f';
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167 break;
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168 }
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169 }
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170 cvalue = (cvalue<<8) | c;
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171 }
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172 return(CONST);
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173
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174 case ALPHA:
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175 if( p = lookup(token) )
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176 expand(p);
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177 else
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1File: CEXPR.C Page 4
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178 return(ALPHA);
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179 break;
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180
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181 default:
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182 return(type);
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183 }
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184 }
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185 }
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186
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187 /* stkop - stack an operator on the operand stack*/
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188 /* Unstack all operators of lower priority, evaluating them as*/
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189 /* they are unstacked.*/
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190 stkop(opr) /* returns 1 if ok, 0 otherwise*/
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191 int opr; /* operator to stack*/
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192 {
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193 register int i, j, op1, op2, pri;
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194
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195 for( pri = opinfo[opr]&OPPRI; pri < *priptr; ) {
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196 if( *oprptr == LPAREN ) {
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197 if( opr == RPAREN ) {
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198 oprptr--;
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199 priptr--;
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200 return(1);
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201 }
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202 break;
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203 }
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204 op1 = *opnptr;
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205 if( (i=opinfo[*oprptr]) & OPBIN ) {
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206 op2 = op1;
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207 op1 = *--opnptr;
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208 }
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209 switch(*oprptr) { /*operator*/
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210
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211 case ADD:
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212 op1 =+ op2;
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213 break;
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214
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215 case SUB:
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216 op1 =- op2;
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217 break;
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218
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219 case COLON:
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220 priptr--;
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221 if( *--oprptr != QMARK )
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222 return(0);
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223 op1 = (*--opnptr ? op1 : op2);
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224 break;
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225
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226 case QMARK:
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227 return(0);
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228
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229 case XOR:
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230 op1 =^ op2;
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231 break;
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232
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233 case OR:
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234 op1 =| op2;
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235 break;
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236
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1File: CEXPR.C Page 5
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237 case AND:
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238 op1 =& op2;
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239 break;
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240
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241 case EQUAL:
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242 op1 = (op1 == op2);
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243 break;
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244
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245 case NEQUAL:
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246 op1 = (op1 != op2);
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247 break;
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248
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249 case LESS:
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250 op1 = (op1 < op2);
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251 break;
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252
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253 case LSEQUAL:
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254 op1 = (op1 <= op2);
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255 break;
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256
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257 case GREAT:
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258 op1 = (op1 > op2);
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259 break;
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260
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261 case GREQUAL:
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262 op1 = (op1 >= op2);
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263 break;
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264
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265 case LSHIFT:
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266 op1 = (op1 << op2);
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267 break;
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268
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269 case RSHIFT:
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270 op1 = (op1 >> op2);
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271 break;
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272
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273 case NEG:
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274 op1 = -op1;
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275 break;
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276
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277 case NOT:
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278 op1 = !op1;
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279 break;
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280
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281 case COMPL:
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282 op1 = ~ op1;
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283 break;
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284
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285 case MULT:
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286 op1 =* op2;
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287 break;
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288
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289 case DIV:
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290 op1 =/ op2;
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291 break;
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292
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293 case MOD:
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294 op1 =% op2;
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295 break;
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1File: CEXPR.C Page 6
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296
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297 }
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298 *opnptr = op1;
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299 priptr--;
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300 oprptr--;
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301 }
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302 if( priptr >= &pristk[STKLEN-1] ) {
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303 error("expression operator stack overflow");
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304 cexit();
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305 }
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306 *++oprptr = opr; /*operator value*/
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307 *++priptr = pri; /*operator priority*/
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308 return(1);
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309 }
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310
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311 #define toupper(c) ((c) & ~32)
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312 /* const - alpha to int conversion, handles octal and hexidecimal*/
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313 /* Uses Horner's method to evaluate number.*/
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314 const(str) /* returns number evaluated*/
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315 char *str; /* pointer to string to convert*/
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316 {
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317 register int c, ch, i, radix;
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318
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319 i = 0;
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320 radix = 10;
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321 if( *str == '0' ) {
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322 radix = 8;
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323 if( *++str == 'x' || *str == 'X' ) {
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324 radix = 16;
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325 str++;
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326 }
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327 }
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328 while( c = *str++ ) {
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329 if( (ch=toupper(c)) >= 'A' && ch <= 'F' )
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330 c = ch - ('A'-10);
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331 else if( c >= '0' && c <= '9' )
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332 c =- '0';
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333 else
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334 break;
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335 if( c >= radix )
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336 break;
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337 i = i*radix + c;
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338 }
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339 return(i);
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340 }
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