tools/mkbridge.c

   1 #include <stdio.h>
   2 #include <stdlib.h>
   3 #include <string.h>
   4
   5 #include "my_assert.h"
   6 #include "my_str.h"
   7
   8 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(x[0]))
   9 #define IS(w, y) !strcmp(w, y)
  10
  11 #include "protoparse.h"
  12
  13 static int is_x86_reg_saved(const char *reg)
  14 {
  15         static const char *nosave_regs[] = { "eax", "edx", "ecx" };
  16         int nosave = 0;
  17         int r;
  18
  19         for (r = 0; r < ARRAY_SIZE(nosave_regs); r++)
  20                 if (strcmp(reg, nosave_regs[r]) == 0)
  21                         nosave = 1;
  22
  23         return !nosave;
  24 }
  25
  26 static void out_toasm_x86(FILE *f, const char *sym_in,
  27         const char *sym_out, const struct parsed_proto *pp)
  28 {
  29         int must_save = 0;
  30         int sarg_ofs = 1; // stack offset to args, in DWORDs
  31         int args_repushed = 0;
  32         int argc_repush;
  33         int i;
  34
  35         argc_repush = pp->argc;
  36         if (pp->is_vararg)
  37                 argc_repush = ARRAY_SIZE(pp->arg); // hopefully enough?
  38
  39         for (i = 0; i < pp->argc; i++) {
  40                 if (pp->arg[i].reg != NULL)
  41                         must_save |= is_x86_reg_saved(pp->arg[i].reg);
  42         }
  43
  44         fprintf(f, ".global %s%s\n", pp->is_fastcall ? "@" : "_", sym_in);
  45         fprintf(f, "%s%s:\n", pp->is_fastcall ? "@" : "_", sym_in);
  46
  47         if (pp->argc_reg == 0 || pp->is_fastcall) {
  48                 fprintf(f, "\t# %s\n",
  49                   pp->is_fastcall ? "__fastcall" :
  50                   (pp->is_stdcall ? "__stdcall" : "__cdecl"));
  51                 fprintf(f, "\tjmp %s\n\n", sym_out);
  52                 return;
  53         }
  54
  55         if (pp->argc_stack == 0 && !must_save && !pp->is_stdcall
  56              && !pp->is_vararg)
  57         {
  58                 // load arg regs
  59                 for (i = 0; i < pp->argc; i++) {
  60                         fprintf(f, "\tmovl %d(%%esp), %%%s\n",
  61                                 (i + sarg_ofs) * 4, pp->arg[i].reg);
  62                 }
  63                 fprintf(f, "\tjmp %s\n\n", sym_out);
  64                 return;
  65         }
  66
  67         // save the regs
  68         for (i = 0; i < pp->argc; i++) {
  69                 if (pp->arg[i].reg != NULL && is_x86_reg_saved(pp->arg[i].reg)) {
  70                         fprintf(f, "\tpushl %%%s\n", pp->arg[i].reg);
  71                         sarg_ofs++;
  72                 }
  73         }
  74
  75         // reconstruct arg stack
  76         for (i = argc_repush - 1; i >= 0; i--) {
  77                 if (pp->arg[i].reg == NULL) {
  78                         fprintf(f, "\tmovl %d(%%esp), %%eax\n",
  79                                 (i + sarg_ofs) * 4);
  80                         fprintf(f, "\tpushl %%eax\n");
  81                         sarg_ofs++;
  82                         args_repushed++;
  83                 }
  84         }
  85         // my_assert(args_repushed, pp->argc_stack);
  86
  87         // load arg regs
  88         for (i = 0; i < pp->argc; i++) {
  89                 if (pp->arg[i].reg != NULL) {
  90                         fprintf(f, "\tmovl %d(%%esp), %%%s\n",
  91                                 (i + sarg_ofs) * 4, pp->arg[i].reg);
  92                 }
  93         }
  94
  95         fprintf(f, "\n\t# %s\n", pp->is_stdcall ? "__stdcall" : "__cdecl");
  96         fprintf(f, "\tcall %s\n\n", sym_out);
  97
  98         if (args_repushed && !pp->is_stdcall)
  99                 fprintf(f, "\tadd $%d,%%esp\n", args_repushed * 4);
 100
 101         // restore regs
 102         for (i = pp->argc - 1; i >= 0; i--) {
 103                 if (pp->arg[i].reg != NULL && is_x86_reg_saved(pp->arg[i].reg))
 104                         fprintf(f, "\tpopl %%%s\n", pp->arg[i].reg);
 105         }
 106
 107         fprintf(f, "\tret\n\n");
 108 }
 109
 110 static void out_fromasm_x86(FILE *f, const char *sym,
 111         const struct parsed_proto *pp)
 112 {
 113         int sarg_ofs = 1; // stack offset to args, in DWORDs
 114         int saved_regs = 0;
 115         int argc_repush;
 116         int stack_args;
 117         int ret64;
 118         int i;
 119
 120         argc_repush = pp->argc;
 121         stack_args = pp->argc_stack;
 122         if (pp->is_vararg) {
 123                 argc_repush = ARRAY_SIZE(pp->arg); // hopefully enough?
 124                 stack_args = argc_repush - pp->argc_reg;
 125         }
 126
 127         ret64 = strstr(pp->ret_type.name, "int64") != NULL;
 128
 129         fprintf(f, "# %s",
 130           pp->is_fastcall ? "__fastcall" :
 131           (pp->is_stdcall ? "__stdcall" : "__cdecl"));
 132         if (ret64)
 133                  fprintf(f, " ret64");
 134         fprintf(f, "\n.global %s\n", sym);
 135         fprintf(f, "%s:\n", sym);
 136
 137         if (pp->argc_reg == 0 || pp->is_fastcall) {
 138                 fprintf(f, "\tjmp %s%s",
 139                         pp->is_fastcall ? "@" : "_", sym);
 140                 if (pp->is_stdcall && pp->argc > 0)
 141                         fprintf(f, "@%d", pp->argc * 4);
 142                 fprintf(f, "\n\n");
 143                 return;
 144         }
 145
 146         // at least sc sub_47B150 needs edx to be preserved
 147         // int64 returns use edx:eax - no edx save
 148         // we use ecx also as scratch
 149         fprintf(f, "\tpushl %%ecx\n");
 150         saved_regs++;
 151         sarg_ofs++;
 152         if (!ret64) {
 153                 fprintf(f, "\tpushl %%edx\n");
 154                 saved_regs++;
 155                 sarg_ofs++;
 156         }
 157
 158         // construct arg stack
 159         for (i = argc_repush - 1; i >= 0; i--) {
 160                 if (pp->arg[i].reg == NULL) {
 161                         fprintf(f, "\tmovl %d(%%esp), %%ecx\n",
 162                                 (sarg_ofs + stack_args - 1) * 4);
 163                         fprintf(f, "\tpushl %%ecx\n");
 164                         stack_args--;
 165                 }
 166                 else {
 167                         if (IS(pp->arg[i].reg, "ecx"))
 168                                 // must reload original ecx
 169                                 fprintf(f, "\tmovl %d(%%esp), %%ecx\n",
 170                                         (sarg_ofs - 2) * 4);
 171
 172                         fprintf(f, "\tpushl %%%s\n", pp->arg[i].reg);
 173                 }
 174                 sarg_ofs++;
 175         }
 176
 177         // no worries about calling conventions - always __cdecl
 178         fprintf(f, "\n\tcall _%s\n\n", sym);
 179
 180         if (sarg_ofs > saved_regs + 1)
 181                 fprintf(f, "\tadd $%d,%%esp\n",
 182                         (sarg_ofs - (saved_regs + 1)) * 4);
 183
 184         if (!ret64)
 185                 fprintf(f, "\tpopl %%edx\n");
 186         fprintf(f, "\tpopl %%ecx\n");
 187
 188         if (pp->is_stdcall && pp->argc_stack)
 189                 fprintf(f, "\tret $%d\n\n", pp->argc_stack * 4);
 190         else
 191                 fprintf(f, "\tret\n\n");
 192 }
 193
 194 int main(int argc, char *argv[])
 195 {
 196         FILE *fout, *fsyms_to, *fsyms_from, *fhdr;
 197         const struct parsed_proto *pp;
 198         char line[256];
 199         char sym_noat[256];
 200         char sym[256];
 201         char *p;
 202         int ret = 1;
 203
 204         if (argc != 5) {
 205                 printf("usage:\n%s <bridge.s> <toasm_symf> <fromasm_symf> <hdrf>\n",
 206                         argv[0]);
 207                 return 1;
 208         }
 209
 210         hdrfn = argv[4];
 211         fhdr = fopen(hdrfn, "r");
 212         my_assert_not(fhdr, NULL);
 213
 214         fsyms_from = fopen(argv[3], "r");
 215         my_assert_not(fsyms_from, NULL);
 216
 217         fsyms_to = fopen(argv[2], "r");
 218         my_assert_not(fsyms_to, NULL);
 219
 220         fout = fopen(argv[1], "w");
 221         my_assert_not(fout, NULL);
 222
 223         fprintf(fout, ".text\n\n");
 224         fprintf(fout, "# to asm\n\n");
 225
 226         while (fgets(line, sizeof(line), fsyms_to))
 227         {
 228                 next_word(sym, sizeof(sym), line);
 229                 if (sym[0] == 0 || sym[0] == ';' || sym[0] == '#')
 230                         continue;
 231
 232                 // IDA asm doesn't do '@' notation..
 233                 strcpy(sym_noat, sym);
 234                 p = strchr(sym_noat, '@');
 235                 if (p != NULL)
 236                         *p = 0;
 237
 238                 pp = proto_parse(fhdr, sym_noat, 0);
 239                 if (pp == NULL)
 240                         goto out;
 241
 242                 out_toasm_x86(fout, sym, sym_noat, pp);
 243         }
 244
 245         fprintf(fout, "# from asm\n\n");
 246
 247         while (fgets(line, sizeof(line), fsyms_from))
 248         {
 249                 next_word(sym, sizeof(sym), line);
 250                 if (sym[0] == 0 || sym[0] == ';' || sym[0] == '#')
 251                         continue;
 252
 253                 pp = proto_parse(fhdr, sym, 0);
 254                 if (pp == NULL)
 255                         goto out;
 256
 257                 out_fromasm_x86(fout, sym, pp);
 258         }
 259
 260         ret = 0;
 261 out:
 262         fclose(fout);
 263         fclose(fsyms_to);
 264         fclose(fsyms_from);
 265         fclose(fhdr);
 266         if (ret)
 267                 remove(argv[1]);
 268
 269         return ret;
 270 }