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, char *sym, struct parsed_proto *pp)
  27 {
  28         int must_save = 0;
  29         int sarg_ofs = 1; // stack offset to args, in DWORDs
  30         int args_repushed = 0;
  31         int argc_repush;
  32         int i;
  33
  34         argc_repush = pp->argc;
  35         if (pp->is_vararg)
  36                 argc_repush = ARRAY_SIZE(pp->arg); // hopefully enough?
  37
  38         for (i = 0; i < pp->argc; i++) {
  39                 if (pp->arg[i].reg != NULL)
  40                         must_save |= is_x86_reg_saved(pp->arg[i].reg);
  41         }
  42
  43         fprintf(f, ".global _%s\n", sym);
  44         fprintf(f, "_%s:\n", sym);
  45
  46         if (pp->argc_reg == 0 && !pp->is_stdcall) {
  47                 fprintf(f, "\tjmp %s\n\n", sym);
  48                 return;
  49         }
  50
  51         if (pp->argc_stack == 0 && !must_save && !pp->is_stdcall
  52              && !pp->is_vararg)
  53         {
  54                 // load arg regs
  55                 for (i = 0; i < pp->argc; i++) {
  56                         fprintf(f, "\tmovl %d(%%esp), %%%s\n",
  57                                 (i + sarg_ofs) * 4, pp->arg[i].reg);
  58                 }
  59                 fprintf(f, "\tjmp %s\n\n", sym);
  60                 return;
  61         }
  62
  63         // save the regs
  64         for (i = 0; i < pp->argc; i++) {
  65                 if (pp->arg[i].reg != NULL && is_x86_reg_saved(pp->arg[i].reg)) {
  66                         fprintf(f, "\tpushl %%%s\n", pp->arg[i].reg);
  67                         sarg_ofs++;
  68                 }
  69         }
  70
  71         // reconstruct arg stack
  72         for (i = argc_repush - 1; i >= 0; i--) {
  73                 if (pp->arg[i].reg == NULL) {
  74                         fprintf(f, "\tmovl %d(%%esp), %%eax\n",
  75                                 (i + sarg_ofs) * 4);
  76                         fprintf(f, "\tpushl %%eax\n");
  77                         sarg_ofs++;
  78                         args_repushed++;
  79                 }
  80         }
  81         // my_assert(args_repushed, pp->argc_stack);
  82
  83         // load arg regs
  84         for (i = 0; i < pp->argc; i++) {
  85                 if (pp->arg[i].reg != NULL) {
  86                         fprintf(f, "\tmovl %d(%%esp), %%%s\n",
  87                                 (i + sarg_ofs) * 4, pp->arg[i].reg);
  88                 }
  89         }
  90
  91         fprintf(f, "\n\t# %s\n", pp->is_stdcall ? "__stdcall" : "__cdecl");
  92         fprintf(f, "\tcall %s\n\n", sym);
  93
  94         if (args_repushed && !pp->is_stdcall)
  95                 fprintf(f, "\tadd $%d,%%esp\n", args_repushed * 4);
  96
  97         // restore regs
  98         for (i = pp->argc - 1; i >= 0; i--) {
  99                 if (pp->arg[i].reg != NULL && is_x86_reg_saved(pp->arg[i].reg))
 100                         fprintf(f, "\tpopl %%%s\n", pp->arg[i].reg);
 101         }
 102
 103         fprintf(f, "\tret\n\n");
 104 }
 105
 106 static void out_fromasm_x86(FILE *f, char *sym, struct parsed_proto *pp)
 107 {
 108         int sarg_ofs = 1; // stack offset to args, in DWORDs
 109         int argc_repush;
 110         int stack_args;
 111         int i;
 112
 113         argc_repush = pp->argc;
 114         stack_args = pp->argc_stack;
 115         if (pp->is_vararg) {
 116                 argc_repush = ARRAY_SIZE(pp->arg); // hopefully enough?
 117                 stack_args = argc_repush - pp->argc_reg;
 118         }
 119
 120         fprintf(f, "# %s\n", pp->is_stdcall ? "__stdcall" : "__cdecl");
 121         fprintf(f, ".global %s\n", sym);
 122         fprintf(f, "%s:\n", sym);
 123
 124         if (pp->argc_reg == 0 && !pp->is_stdcall) {
 125                 fprintf(f, "\tjmp _%s\n\n", sym);
 126                 return;
 127         }
 128
 129         fprintf(f, "\tpushl %%edx\n"); // just in case..
 130         sarg_ofs++;
 131
 132         // construct arg stack
 133         for (i = argc_repush - 1; i >= 0; i--) {
 134                 if (pp->arg[i].reg == NULL) {
 135                         fprintf(f, "\tmovl %d(%%esp), %%edx\n",
 136                                 (sarg_ofs + stack_args - 1) * 4);
 137                         fprintf(f, "\tpushl %%edx\n");
 138                         stack_args--;
 139                 }
 140                 else {
 141                         if (IS(pp->arg[i].reg, "edx"))
 142                                 // must reload original edx
 143                                 fprintf(f, "\tmovl %d(%%esp), %%edx\n",
 144                                         (sarg_ofs - 2) * 4);
 145
 146                         fprintf(f, "\tpushl %%%s\n", pp->arg[i].reg);
 147                 }
 148                 sarg_ofs++;
 149         }
 150
 151         // no worries about calling conventions - always __cdecl
 152         fprintf(f, "\n\tcall _%s\n\n", sym);
 153
 154         if (sarg_ofs > 2)
 155                 fprintf(f, "\tadd $%d,%%esp\n", (sarg_ofs - 2) * 4);
 156
 157         fprintf(f, "\tpopl %%edx\n");
 158
 159         if (pp->is_stdcall && pp->argc_stack)
 160                 fprintf(f, "\tret $%d\n\n", pp->argc_stack * 4);
 161         else
 162                 fprintf(f, "\tret\n\n");
 163 }
 164
 165 int main(int argc, char *argv[])
 166 {
 167         FILE *fout, *fsyms_to, *fsyms_from, *fhdr;
 168         struct parsed_proto pp;
 169         char line[256];
 170         char sym[256];
 171         int ret;
 172
 173         if (argc != 5) {
 174                 printf("usage:\n%s <bridge.s> <toasm_symf> <fromasm_symf> <hdrf>\n",
 175                         argv[0]);
 176                 return 1;
 177         }
 178
 179         hdrfn = argv[4];
 180         fhdr = fopen(hdrfn, "r");
 181         my_assert_not(fhdr, NULL);
 182
 183         fsyms_from = fopen(argv[3], "r");
 184         my_assert_not(fsyms_from, NULL);
 185
 186         fsyms_to = fopen(argv[2], "r");
 187         my_assert_not(fsyms_to, NULL);
 188
 189         fout = fopen(argv[1], "w");
 190         my_assert_not(fout, NULL);
 191
 192         fprintf(fout, ".text\n\n");
 193         fprintf(fout, "# to asm\n\n");
 194
 195         while (fgets(line, sizeof(line), fsyms_to))
 196         {
 197                 next_word(sym, sizeof(sym), line);
 198                 if (sym[0] == 0 || sym[0] == ';' || sym[0] == '#')
 199                         continue;
 200
 201                 ret = proto_parse(fhdr, sym, &pp);
 202                 if (ret)
 203                         goto out;
 204
 205                 out_toasm_x86(fout, sym, &pp);
 206                 proto_release(&pp);
 207         }
 208
 209         fprintf(fout, "# from asm\n\n");
 210
 211         while (fgets(line, sizeof(line), fsyms_from))
 212         {
 213                 next_word(sym, sizeof(sym), line);
 214                 if (sym[0] == 0 || sym[0] == ';' || sym[0] == '#')
 215                         continue;
 216
 217                 ret = proto_parse(fhdr, sym, &pp);
 218                 if (ret)
 219                         goto out;
 220
 221                 out_fromasm_x86(fout, sym, &pp);
 222                 proto_release(&pp);
 223         }
 224
 225         ret = 0;
 226 out:
 227         fclose(fout);
 228         fclose(fsyms_to);
 229         fclose(fsyms_from);
 230         fclose(fhdr);
 231         if (ret)
 232                 remove(argv[1]);
 233
 234         return ret;
 235 }