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1 /*
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2 insn_rel.c
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3 Copyright © 2009 William Astle
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4
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5 This file is part of LWASM.
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6
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7 LWASM 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 /*
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22 for handling relative mode instructions
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23 */
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24
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25 #define __insn_rel_c_seen__
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26 #include <config.h>
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27 #include <stdlib.h>
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28
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29 #include "expr.h"
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30 #include "lwasm.h"
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31 #include "instab.h"
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32
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33 OPFUNC(insn_rel8)
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34 {
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35 int v;
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36 lwasm_expr_term_t *t;
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37 int r;
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38
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39 lwasm_emitop(as, l, instab[opnum].ops[0]);
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40
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41 if (**p == '#')
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42 (*p)++;
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43
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44 if ((r = lwasm_expr_result2(as, l, p, EXPR_SECTCONST, &v, 0)) < 0)
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45 v = 0;
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46 else
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47 {
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48 if (as -> passnum == 1)
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49 {
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50 // need to adjust the expression
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51 if (l -> exprs[0])
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52 {
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53 t = lwasm_expr_term_create_int(as -> addr + 1);
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54 lwasm_expr_stack_push(l -> exprs[0], t);
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55 lwasm_expr_term_free(t);
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56 t = lwasm_expr_term_create_oper(LWASM_OPER_MINUS);
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57 lwasm_expr_stack_push(l -> exprs[0], t);
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58 lwasm_expr_term_free(t);
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59 }
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60 else
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61 {
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62 l -> exprvals[0] -= as -> addr + 1;
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63 }
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64 }
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65 }
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66 if (r == 1 && as -> passnum == 2)
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67 {
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68 register_error(as, l, 2, "Illegal external or intersegment reference");
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69 }
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70 if (v < -128 || v > 127)
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71 register_error(as, l, 2, "Byte overflow");
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72 lwasm_emit(as, l, v & 0xff);
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73 }
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74
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75 /*
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76 External and intersegment references are adjusted for the relative addressing mode
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77 by adjusting the expression on pass 1 and then treated as absolute references later
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78 */
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79 OPFUNC(insn_rel16)
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80 {
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81 int v;
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82 int r;
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83 lwasm_expr_term_t *t;
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84
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85 lwasm_emitop(as, l, instab[opnum].ops[0]);
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86
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87 if (**p == '#')
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88 (*p)++;
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89
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90 r = lwasm_expr_result2(as, l, p, EXPR_SECTCONST, &v, 0);
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91 if (r < 0)
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92 v = 0;
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93 else
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94 {
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95 if (as -> passnum == 1)
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96 {
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97 // need to adjust the expression
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98 if (l -> exprs[0])
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99 {
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100 t = lwasm_expr_term_create_int(as -> addr + 2);
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101 lwasm_expr_stack_push(l -> exprs[0], t);
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102 lwasm_expr_term_free(t);
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103 t = lwasm_expr_term_create_oper(LWASM_OPER_MINUS);
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104 lwasm_expr_stack_push(l -> exprs[0], t);
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105 lwasm_expr_term_free(t);
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106 }
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107 else
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108 {
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109 l -> exprvals[0] -= as -> addr + 2;
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110 }
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111 }
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112 }
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113 if (as -> passnum == 2 && r == 1)
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114 {
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115 // since we have a reference outside this section, add
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116 // a subtract of the section base to get the right value
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117 // upon linking
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118 t = lwasm_expr_term_create_secbase();
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119 lwasm_expr_stack_push(l -> exprs[0], t);
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120 lwasm_expr_term_free(t);
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121 t = lwasm_expr_term_create_oper(LWASM_OPER_MINUS);
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122 lwasm_expr_stack_push(l -> exprs[0], t);
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123 lwasm_expr_term_free(t);
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124
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125 l -> relocoff = as -> addr - l -> codeaddr;
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126 }
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127 lwasm_emit(as, l, (v >> 8) & 0xff);
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128 lwasm_emit(as, l, v & 0xff);
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129 }
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