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1 /*
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2 * index.c
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3 *
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4 * code for parsing indexed addressing modes
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5 */
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6
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7 #include <ctype.h>
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8 //#include <errno.h>
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9 //#include <stdio.h>
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10 //#include <stdlib.h>
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11 #include <string.h>
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12 #define __index_c_seen__
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13 //#include "instab.h"
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14 #include "lwasm.h"
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15 #include "instab.h"
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16
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17
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18 int parse_index_expr(asmstate_t *as, sourceline_t *cl, char **optr, int *postbyte, int *opmode, int *v1)
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19 {
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20 static const char *regs = "X Y U S W PCRPC ";
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21 static const struct { char *opstr; int pb; } simpleindex[] =
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22 {
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23 {",x", 0x84}, {",y", 0xa4}, {",u", 0xc4}, {",s", 0xe4},
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24 {",x+", 0x80}, {",y+", 0xa0}, {",u+", 0xc0}, {",s+", 0xe0},
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25 {",x++", 0x81}, {",y++", 0xa1}, {",u++", 0xc1}, {",s++", 0xe1},
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26 {",-x", 0x82}, {",-y", 0xa2}, {",-u", 0xc2}, {",-s", 0xe2},
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27 {",--x", 0x83}, {",--y", 0xa3}, {",--u", 0xc3}, {",--s", 0xe3},
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28 {"a,x", 0x86}, {"a,y", 0xa6}, {"a,u", 0xc6}, {"a,s", 0xe6},
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29 {"b,x", 0x85}, {"b,y", 0xa5}, {"b,u", 0xc5}, {"b,s", 0xe5},
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30 {"e,x", 0x87}, {"e,y", 0xa7}, {"e,u", 0xc7}, {"e,s", 0xe7},
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31 {"f,x", 0x8a}, {"f,y", 0xaa}, {"f,u", 0xca}, {"f,s", 0xea},
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32 {"d,x", 0x8b}, {"d,y", 0xab}, {"d,u", 0xcb}, {"d,s", 0xed},
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33 {"w,x", 0x8e}, {"w,y", 0xae}, {"w,u", 0xce}, {"w,s", 0xee},
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34 {",w", 0x8f}, {",w++", 0xcf}, {",--w", 0xef},
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35
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36 {"[,x]", 0x94}, {"[,y]", 0xb4}, {"[,u", 0xd4}, {"[,s]", 0xf4},
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37 {"[,x++]", 0x91}, {"[,y++]", 0xb1}, {"[,u++]", 0xd1}, {"[,s++]", 0xf1},
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38 {"[,--x]", 0x93}, {"[,--y]", 0xb3}, {"[,--u]", 0xd3}, {"[,--s]", 0xf3},
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39 {"[a,x]", 0x96}, {"[a,y]", 0xb6}, {"[a,u]", 0xd6}, {"[a,s]", 0xf6},
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40 {"[b,x]", 0x95}, {"[b,y]", 0xb5}, {"[b,u]", 0xd5}, {"[b,s]", 0xf5},
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41 {"[e,x]", 0x97}, {"[e,y]", 0xb7}, {"[e,u]", 0xd7}, {"[e,s]", 0xf7},
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42 {"[f,x]", 0x9a}, {"[f,y]", 0xba}, {"[f,u]", 0xda}, {"[f,s]", 0xfa},
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43 {"[d,x]", 0x9b}, {"[d,y]", 0xbb}, {"[d,u]", 0xdb}, {"[d,s]", 0xfd},
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44 {"[w,x]", 0x9e}, {"[w,y]", 0xbe}, {"[w,u]", 0xde}, {"[w,s]", 0xfe},
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45 {"[,w]", 0x90}, {"[,w++]", 0xd0}, {"[,--w]", 0xf0},
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46
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47 { "", -1 }
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48 };
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49 char stbuf[25];
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50 int i;
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51 int f8 = 0, f16 = 0;
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52 int rn;
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53 int indir = 0;
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54 int rval;
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55 int f0 = 0;
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56
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57 for (i = 0; i < 24; i++)
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58 {
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59 if (*((*optr) + i) && !isspace(*((*optr) + i)))
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60 stbuf[i] = *((*optr) + i);
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61 else
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62 break;
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63 }
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64 stbuf[i] = '\0';
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65 if (!*((*optr) + i) || isspace(*((*optr) + i)))
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66 {
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67 int j;
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68 // do simple lookup
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69 for (j = 0; simpleindex[j].opstr[0]; j++)
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70 {
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71 if (!strcasecmp(stbuf, simpleindex[j].opstr))
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72 break;
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73 }
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74 if (simpleindex[j].opstr[0])
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75 {
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76 *postbyte = simpleindex[j].pb;
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77 *opmode = OPER_INDEX;
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78 (*optr) += i;
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79 return 0;
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80 }
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81 }
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82
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83 // now we have the hard ones to work out here
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84
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85 if (**optr == '[')
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86 {
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87 indir = 1;
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88 (*optr)++;
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89 }
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90
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91 rn = 0;
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92 for (i = 0; (*optr)[i] && !isspace((*optr)[i]); i++)
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93 {
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94 if ((*optr)[i] == ',')
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95 {
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96 rn = 1;
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97 break;
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98 }
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99 }
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100
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101 if (!rn && indir)
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102 {
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103 // extended indir
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104 *postbyte = 0x9f;
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105 *opmode = OPER_EXTIND;
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106 rval = eval_expr(as, cl, optr, v1);
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107 if (**optr != ']')
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108 {
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109 errorp1(ERR_BADOPER);
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110 }
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111 (*optr)++;
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112 return 0;
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113 }
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114
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115 if (cl -> p1f16)
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116 f16 = 1;
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117 if (**optr == '<')
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118 {
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119 f8 = 1;
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120 (*optr)++;
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121 }
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122 else if (**optr == '>')
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123 {
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124 f16 = 1;
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125 (*optr)++;
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126 }
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127
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128 if (**optr == '0' && *(*optr+1) == ',')
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129 {
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130 f0 = 1;
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131 }
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132
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133 // now we have to evaluate the expression
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134 rval = eval_expr(as, cl, optr, v1);
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135
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136 if (cl -> undef && as -> passnum == 1)
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137 {
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138 cl -> p1f16 = 1;
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139 f16 = 1;
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140 }
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141
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142 // now look for a comma; if not present, explode
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143 if (rval == -1 || *(*optr)++ != ',')
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144 {
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145 // syntax error; force 0 bit
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146 *postbyte = -1;
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147 *opmode = OPER_INDEX;
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148 return -2;
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149 }
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150
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151 // now get the register
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152 rn = lookupreg3(regs, optr);
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153 if (rn < 0)
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154 goto reterr;
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155
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156 // debug("Reg: %d\n", rn);
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157
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158 if (indir && **optr != ']')
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159 goto reterr;
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160 else
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161 (*optr)++;
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162
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163 // nnnn,W is only 16 bit
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164 if (rn == 4)
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165 {
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166 if (f8)
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167 goto reterr;
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168 if (!f16 && !f0 && !(as -> pragmas & PRAGMA_NOINDEX0TONONE) && *v1 == 0)
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169 {
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170 *opmode = OPER_INDEX;
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171 if (indir)
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172 *postbyte = 0x90;
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173 else
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174 *postbyte = 0x8f;
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175 return 0;
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176 }
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177 *opmode = OPER_INDEX16;
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178 if (indir)
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179 *postbyte = 0xb0;
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180 else
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181 *postbyte = 0xcf;
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182 return 0;
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183 }
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184
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185 if (indir) indir = 0x10;
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186
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187 // forward ref; we can't figure anything
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188 if (cl -> undef)
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189 {
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190 f16 = 1;
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191 }
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192
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193 // PCR? redo v1, v2 relative to current address
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194 if (rn == 5)
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195 {
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196 *v1 -= as -> addr;
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197
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198 // we have a slight problem here
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199 // PCR based on current insn loc is really
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200 // -125 <= offset <= +130 (8 bit offset)
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201 if (f8 || (!f16 && *v1 >= -125 && *v1 <= 130))
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202 {
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203 *opmode = OPER_INDEX8;
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204 *postbyte = indir | 0x8C;
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205 *v1 -= 3;
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206 if (*v1 < -128 || *v1 > 127)
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207 errorp2(ERR_OVERFLOW);
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208 return 0;
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209 }
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210
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211 // anything else is 16 bit offset
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212 // need 16 bit
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213 *opmode = OPER_INDEX16;
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214 *postbyte = indir | 0x8D;
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215 *v1 -= 4;
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216 return 0;
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217 }
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218
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219 // constant offset from PC
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220 if (rn == 6)
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221 {
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222 if (f8 || (!f16 && *v1 >= -128 && *v1 <= 127))
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223 {
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224 *opmode = OPER_INDEX8;
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225 *postbyte = indir | 0x8C;
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226 if (*v1 < -128 || *v1 > 127)
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227 errorp2(ERR_OVERFLOW);
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228 return 0;
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229 }
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230
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231 // everything else must be 16 bit
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232 // need 16 bit
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233 *opmode = OPER_INDEX16;
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234 *postbyte = indir | 0x8D;
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235 return 0;
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236
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237 }
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238
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239 // we only have to deal with x,y,u,s here
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240 if (!f8 && !f16 && *v1 >= -16 && *v1 <= 15)
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241 {
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242 if (*v1 == 0 && !f0 && !(as -> pragmas & PRAGMA_NOINDEX0TONONE))
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243 {
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244 *postbyte = rn << 5 | indir | 0x80 | 0x04;
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245 *opmode = OPER_INDEX;
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246 return 0;
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247 }
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248 // we pick the smallest value here
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249 if (indir)
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250 {
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251 f8 = 1;
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252 goto no5bit;
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253 }
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254 *postbyte = rn << 5 | (*v1 & 0x1F);
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255 *opmode = OPER_INDEX5;
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256 return 0;
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257 }
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258 no5bit:
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259 if (f16 || (!f8 && (*v1 < -128 || *v1 > 127)))
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260 {
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261 // must be a 16 bit offset here
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262 *postbyte = rn << 5 | indir | 0x80 | 0x09;
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263 *opmode = OPER_INDEX16;
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264 return 0;
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265 }
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266
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267 // if we're here, we have an 8 bit offset
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268 *postbyte = rn << 5 | indir | 0x80 | 0x08;
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269 *opmode = OPER_INDEX8;
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270 if (*v1 < -128 || *v1 > 127)
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271 errorp2(ERR_OVERFLOW);
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272 return 0;
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273 reterr:
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274 *postbyte = -1;
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275 *opmode = OPER_INDEX;
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276 return -2;
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277 }
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278
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279 void insn_indexed_aux(asmstate_t *as, sourceline_t *cl, char **optr, int *b1, int *b2, int *b3)
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280 {
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281 int rval;
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282 int v1, pb = -1;
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283
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284 *b1 = *b2 = *b3 = -1;
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285
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286 rval = parse_index_expr(as, cl, optr, &pb, &(cl -> addrmode), &v1);
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287 if (rval < 0)
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288 errorp1(ERR_BADOPER);
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289 *b1 = pb;
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290
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291 if (cl -> addrmode == OPER_INDEX8)
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292 {
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293 *b2 = v1 & 0xff;
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294 }
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295 else if (cl -> addrmode == OPER_INDEX16 || cl -> addrmode == OPER_EXTIND)
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296 {
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297 *b2 = (v1 & 0xffff) >> 8;
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298 *b3 = v1 & 0xff;
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299 }
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300 }
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301
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302 void insn_indexed(asmstate_t *as, sourceline_t *cl, char **optr)
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303 {
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304 int b1, b2, b3;
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305
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306 emitop(instab[cl -> opcode].ops[0]);
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307 insn_indexed_aux(as, cl, optr, &b1, &b2, &b3);
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308 if (b1 != -1)
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309 emit(b1);
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310 if (b2 != -1)
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311 emit(b2);
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312 if (b3 != -1)
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313 emit(b3);
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314 }
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315
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