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1 /*
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2 readfiles.c
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300
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3 Copyright © 2009 William Astle
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298
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4
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5 This file is part of LWLINK.
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6
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7 LWLINK is free software: you can redistribute it and/or modify it under the
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8 terms of the GNU General Public License as published by the Free Software
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9 Foundation, either version 3 of the License, or (at your option) any later
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10 version.
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11
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12 This program is distributed in the hope that it will be useful, but WITHOUT
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13 ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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14 FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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15 more details.
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16
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17 You should have received a copy of the GNU General Public License along with
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18 this program. If not, see <http://www.gnu.org/licenses/>.
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19
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20
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21 Reads input files
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22
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23 */
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24
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25 #ifdef HAVE_CONFIG_H
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26 #include "config.h"
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27 #endif
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28
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29 #include <argp.h>
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30 #include <errno.h>
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31 #include <stdio.h>
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32 #include <stdlib.h>
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33
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34 #include "lwlink.h"
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35 #include "util.h"
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36
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37 void read_lwobj16v0(fileinfo_t *fn);
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38
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39 /*
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40 The logic of reading the entire file into memory is simple. All the symbol
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41 names in the file are NUL terminated strings and can be used directly without
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42 making additional copies.
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43 */
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44 void read_files(void)
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45 {
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46 int i;
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47 long size;
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48 FILE *f;
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49 long bread;
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50 for (i = 0; i < ninputfiles; i++)
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51 {
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52 f = fopen(inputfiles[i] -> filename, "rb");
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53 if (!f)
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54 {
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55 fprintf(stderr, "Can't open file %s:", inputfiles[i] -> filename);
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56 perror("");
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57 exit(1);
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58 }
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59 fseek(f, 0, SEEK_END);
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60 size = ftell(f);
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61 rewind(f);
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62
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63 inputfiles[i] -> filedata = lw_malloc(size);
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64 inputfiles[i] -> filesize = size;
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65
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66 bread = fread(inputfiles[i] -> filedata, 1, size, f);
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67 if (bread < size)
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68 {
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69 fprintf(stderr, "Short read on file %s (%ld/%ld):", inputfiles[i] -> filename, bread, size);
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70 perror("");
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71 exit(1);
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72 }
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73
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74 fclose(f);
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75
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76 if (!memcmp(inputfiles[i] -> filedata, "LWOBJ16", 8))
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77 {
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78 // read v0 LWOBJ16 file
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79 read_lwobj16v0(inputfiles[i]);
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80 }
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81 else
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82 {
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83 fprintf(stderr, "%s: unknown file format\n", inputfiles[i] -> filename);
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84 exit(1);
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85 }
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86 }
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87 }
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88
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89 // this macro is used to bail out if we run off the end of the file data
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90 // while parsing - it keeps the code below cleaner
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91 #define NEXTBYTE() do { cc++; if (cc >= fn -> filesize) { fprintf(stderr, "%s: invalid file format\n", fn -> filename); exit(1); } } while (0)
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92 // this macro is used to refer to the current byte in the stream
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93 #define CURBYTE() (fn -> filedata[cc])
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94 // this one will leave the input pointer past the trailing NUL
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95 #define CURSTR() read_lwobj16v0_str(&cc, fn)
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96 unsigned char *read_lwobj16v0_str(long *cc1, fileinfo_t *fn)
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97 {
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98 int cc = *cc1;
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99 unsigned char *fp;
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100 fp = &CURBYTE();
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101 while (CURBYTE())
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102 NEXTBYTE();
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103 NEXTBYTE();
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104 *cc1 = cc;
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105 return fp;
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106 }
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107 // the function below can be switched to dealing with data coming from a
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108 // source other than an in-memory byte pool by adjusting the input data
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109 // in "fn" and the above two macros
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110 void read_lwobj16v0(fileinfo_t *fn)
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111 {
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112 unsigned char *fp;
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113 long cc;
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114 section_t *s;
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115 int val;
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116 symtab_t *se;
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117
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118 // start reading *after* the magic number
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119 cc = 7;
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120
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121 // init data
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122 fn -> sections = NULL;
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123 fn -> nsections = 0;
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124
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125 while (1)
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126 {
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127 NEXTBYTE();
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128 // bail out if no more sections
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129 if (!(CURBYTE()))
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130 break;
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131
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132 fp = CURSTR();
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133
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134 // we now have a section name in fp
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135 // create new section entry
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136 fn -> sections = lw_realloc(fn -> sections, sizeof(section_t) * (fn -> nsections + 1));
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137 s = &(fn -> sections[fn -> nsections]);
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138 fn -> nsections += 1;
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139
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140 s -> localsyms = NULL;
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141 s -> flags = 0;
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142 s -> codesize = 0;
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143 s -> name = fp;
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144 s -> loadaddress = 0;
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145 s -> localsyms = NULL;
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146 s -> exportedsyms = NULL;
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147 s -> incompletes = NULL;
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148
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149 // read flags
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150 while (CURBYTE())
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151 {
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152 switch (CURBYTE())
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153 {
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154 case 0x01:
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155 s -> flags |= SECTION_BSS;
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156 break;
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157
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158 default:
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159 fprintf(stderr, "%s (%s): unrecognized section flag %02X\n", fn -> filename, s -> name, (int)(CURBYTE()));
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160 exit(1);
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161 }
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162 NEXTBYTE();
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163 }
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164 // skip NUL terminating flags
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165 NEXTBYTE();
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166
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167 // now parse the local symbol table
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168 while (CURBYTE())
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169 {
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170 fp = CURSTR();
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171
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172 // fp is the symbol name
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173 val = (CURBYTE()) << 8;
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174 NEXTBYTE();
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175 val |= (CURBYTE());
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176 NEXTBYTE();
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177 // val is now the symbol value
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178
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179 // create symbol table entry
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180 se = lw_malloc(sizeof(symtab_t));
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181 se -> next = s -> localsyms;
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182 s -> localsyms = se;
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183 se -> sym = fp;
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184 se -> offset = val;
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185 se -> realval = val;
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186 }
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187
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188 // now parse the exported symbol table
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189 while (CURBYTE())
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190 {
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191 fp = CURSTR();
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192
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193 // fp is the symbol name
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194 val = (CURBYTE()) << 8;
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195 NEXTBYTE();
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196 val |= (CURBYTE());
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197 NEXTBYTE();
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198 // val is now the symbol value
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199
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200 // create symbol table entry
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201 se = lw_malloc(sizeof(symtab_t));
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202 se -> next = s -> exportedsyms;
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203 s -> localsyms = se;
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204 se -> sym = fp;
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205 se -> offset = val;
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206 se -> realval = val;
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207 }
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208
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209 // now parse the incomplete references and make a list of
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210 // external references that need resolution
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211 while (CURBYTE())
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212 {
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213 reloc_t *rp;
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214 lw_expr_term_t *term;
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215
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216 // we have a reference
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217 rp = lw_malloc(sizeof(reloc_t));
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218 rp -> next = s -> incompletes;
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219 s -> incompletes = rp;
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220 rp -> offset = 0;
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221 rp -> expr = lw_expr_stack_create();
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222
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223 // parse the expression
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224 while (CURBYTE())
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225 {
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226 int tt = CURBYTE();
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227 NEXTBYTE();
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228 switch (tt)
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229 {
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230 case 0x01:
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231 // 16 bit integer
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232 tt = CURBYTE() << 8;
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233 NEXTBYTE();
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234 tt |= CURBYTE();
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235 NEXTBYTE();
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236 // normalize for negatives...
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237 if (tt > 0x7fff)
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238 tt -= 0x10000;
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239 term = lw_expr_term_create_int(tt);
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240 break;
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241
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242 case 0x02:
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243 // external symbol reference
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244 term = lw_expr_term_create_sym(CURSTR(), 0);
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245 break;
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246
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247 case 0x03:
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248 // internal symbol reference
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249 term = lw_expr_term_create_sym(CURSTR(), 1);
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250 break;
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251
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252 case 0x04:
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253 // operator
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254 term = lw_expr_term_create_oper(CURBYTE());
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255 NEXTBYTE();
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256 break;
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257
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258 case 0x05:
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259 // section base reference (NULL internal reference is
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260 // the section base address
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261 term = lw_expr_term_create_sym(NULL, 0);
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262 break;
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263
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264 default:
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265 fprintf(stderr, "%s (%s): bad relocation expression\n", fn -> filename, s -> name);
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266 exit(1);
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267 }
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268 lw_expr_stack_push(rp -> expr, term);
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269 lw_expr_term_free(term);
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270 }
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271 }
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272 // skip the NUL terminatin
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273 NEXTBYTE();
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274
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275 // now set code location and size and verify that the file
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276 // contains data going to the end of the code (if !SECTION_BSS)
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277 s -> codesize = CURBYTE() << 8;
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278 NEXTBYTE();
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279 s -> codesize |= CURBYTE();
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280 NEXTBYTE();
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281
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282 s -> code = &(CURBYTE());
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283
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284 // skip the code if we're not in a BSS section
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285 if (!(s -> flags & SECTION_BSS))
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286 {
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287 int i;
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288 for (i = 0; i < s -> codesize; i++)
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289 NEXTBYTE();
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290 }
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291 }
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292 }
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