gas.c

   1 #include "all.h"
   2
   3
   4 char *gasloc, *gassym;
   5
   6 void
   7 gasemitlnk(char *n, Lnk *l, char *s, FILE *f)
   8 {
   9         char *p;
  10
  11         if (l->sec) {
  12                 fprintf(f, ".section %s", l->sec);
  13                 if (l->secf)
  14                         fprintf(f, ", %s", l->secf);
  15         } else {
  16                 fputs(s, f);
  17         }
  18         fputc('\n', f);
  19         if (l->align)
  20                 fprintf(f, ".balign %d\n", l->align);
  21         p = n[0] == '"' ? "" : gassym;
  22         if (l->export)
  23                 fprintf(f, ".globl %s%s\n", p, n);
  24         fprintf(f, "%s%s:\n", p, n);
  25 }
  26
  27 void
  28 gasemitdat(Dat *d, FILE *f)
  29 {
  30         static char *dtoa[] = {
  31                 [DB] = "\t.byte",
  32                 [DH] = "\t.short",
  33                 [DW] = "\t.int",
  34                 [DL] = "\t.quad"
  35         };
  36         static int64_t zero;
  37         char *p;
  38
  39         switch (d->type) {
  40         case DStart:
  41                 zero = 0;
  42                 break;
  43         case DEnd:
  44                 if (zero != -1) {
  45                         gasemitlnk(d->name, d->lnk, ".bss", f);
  46                         fprintf(f, "\t.fill %"PRId64",1,0\n", zero);
  47                 }
  48                 break;
  49         case DZ:
  50                 if (zero != -1)
  51                         zero += d->u.num;
  52                 else
  53                         fprintf(f, "\t.fill %"PRId64",1,0\n", d->u.num);
  54                 break;
  55         default:
  56                 if (zero != -1) {
  57                         gasemitlnk(d->name, d->lnk, ".data", f);
  58                         if (zero > 0)
  59                                 fprintf(f, "\t.fill %"PRId64",1,0\n", zero);
  60                         zero = -1;
  61                 }
  62                 if (d->isstr) {
  63                         if (d->type != DB)
  64                                 err("strings only supported for 'b' currently");
  65                         fprintf(f, "\t.ascii %s\n", d->u.str);
  66                 }
  67                 else if (d->isref) {
  68                         p = d->u.ref.name[0] == '"' ? "" : gassym;
  69                         fprintf(f, "%s %s%s%+"PRId64"\n",
  70                                 dtoa[d->type], p, d->u.ref.name,
  71                                 d->u.ref.off);
  72                 }
  73                 else {
  74                         fprintf(f, "%s %"PRId64"\n",
  75                                 dtoa[d->type], d->u.num);
  76                 }
  77                 break;
  78         }
  79 }
  80
  81 typedef struct Asmbits Asmbits;
  82
  83 struct Asmbits {
  84         char bits[16];
  85         int size;
  86         Asmbits *link;
  87 };
  88
  89 static Asmbits *stash;
  90
  91 int
  92 gasstash(void *bits, int size)
  93 {
  94         Asmbits **pb, *b;
  95         int i;
  96
  97         assert(size == 4 || size == 8 || size == 16);
  98         for (pb=&stash, i=0; (b=*pb); pb=&b->link, i++)
  99                 if (size <= b->size)
 100                 if (memcmp(bits, b->bits, size) == 0)
 101                         return i;
 102         b = emalloc(sizeof *b);
 103         memcpy(b->bits, bits, size);
 104         b->size = size;
 105         b->link = 0;
 106         *pb = b;
 107         return i;
 108 }
 109
 110 void
 111 gasemitfin(FILE *f)
 112 {
 113         Asmbits *b;
 114         char *p;
 115         int sz, i;
 116         double d;
 117
 118         if (!stash)
 119                 return;
 120         fprintf(f, "/* floating point constants */\n.data\n");
 121         for (sz=16; sz>=4; sz/=2)
 122                 for (b=stash, i=0; b; b=b->link, i++) {
 123                         if (b->size == sz) {
 124                                 fprintf(f,
 125                                         ".balign %d\n"
 126                                         "%sfp%d:",
 127                                         sz, gasloc, i
 128                                 );
 129                                 for (p=b->bits; p<&b->bits[sz]; p+=4)
 130                                         fprintf(f, "\n\t.int %"PRId32,
 131                                                 *(int32_t *)p);
 132                                 if (sz <= 8) {
 133                                         if (sz == 4)
 134                                                 d = *(float *)b->bits;
 135                                         else
 136                                                 d = *(double *)b->bits;
 137                                         fprintf(f, " /* %f */\n", d);
 138                                 } else
 139                                         fprintf(f, "\n");
 140                         }
 141                 }
 142         while ((b=stash)) {
 143                 stash = b->link;
 144                 free(b);
 145         }
 146 }