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29
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1 /*
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2 insn_rel.c
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3 Copyright © 2008 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_inh_c_seen__
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26
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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 lwasm_expr_stack_t *s;
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36 int v;
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37
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38 lwasm_emitop(as, l, instab[opnum].ops[0]);
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39
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40 s = lwasm_expr_eval(*p, NULL);
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41 if (!s)
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42 {
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43 register_error(as, l, 1, "Bad operand");
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44 lwasm_emitop(as, l, 0);
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45 return;
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46 }
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47 if (lwasm_expr_is_constant(s))
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48 register_error(as, l, 2, "Incomplete reference");
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49 v = lwasm_expr_get_value(s);
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50 v -= as -> addr + 1;
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51 if (v < -128 || v > 127)
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52 register_error(as, l, 2, "Byte overflow");
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53 lwasm_emit(as, l, v & 0xff);
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54
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55 lwasm_expr_stack_free(s);
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56 }
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57
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58 OPFUNC(insn_rel16)
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59 {
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60 lwasm_expr_stack_t *s;
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61 int v;
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62
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63 lwasm_emitop(as, l, instab[opnum].ops[0]);
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64
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65 s = lwasm_expr_eval(*p, NULL);
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66 if (!s)
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67 {
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68 register_error(as, l, 1, "Bad operand");
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69 lwasm_emitop(as, l, 0);
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70 return;
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71 }
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72 if (lwasm_expr_is_constant(s))
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73 register_error(as, l, 2, "Incomplete reference");
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74 v = lwasm_expr_get_value(s);
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75 v -= as -> addr + 2;
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76 lwasm_emit(as, l, (v >> 8) & 0xff);
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77 lwasm_emit(as, l, v & 0xff);
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78
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79 lwasm_expr_stack_free(s);
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80 }
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