gas.c

См. документацию.

#include "all.h"


char *gasloc, *gassym;

void
gasemitdat(Dat *d, FILE *f)
{
    static int align;
    static char *dtoa[] = {
        [DAlign] = ".align",
        [DB] = "\t.byte",
        [DH] = "\t.short",
        [DW] = "\t.int",
        [DL] = "\t.quad"
    };

    switch (d->type) {
    case DStart:
        align = 0;
        fprintf(f, ".data\n");
        break;
    case DEnd:
        break;
    case DName:
        if (!align)
            fprintf(f, ".align 8\n");
        if (d->export)
            fprintf(f, ".globl %s%s\n", gassym, d->u.str);
        fprintf(f, "%s%s:\n", gassym, d->u.str);
        break;
    case DZ:
        fprintf(f, "\t.fill %"PRId64",1,0\n", d->u.num);
        break;
    default:
        if (d->type == DAlign)
            align = 1;

        if (d->isstr) {
            if (d->type != DB)
                err("strings only supported for 'b' currently");
            fprintf(f, "\t.ascii \"%s\"\n", d->u.str);
        }
        else if (d->isref) {
            fprintf(f, "%s %s%+"PRId64"\n",
                dtoa[d->type], d->u.ref.nam,
                d->u.ref.off);
        }
        else {
            fprintf(f, "%s %"PRId64"\n",
                dtoa[d->type], d->u.num);
        }
        break;
    }
}

typedef struct Asmbits Asmbits;

struct Asmbits {
    char bits[16];
    int size;
    Asmbits *link;
};

static Asmbits *stash;

int
gasstash(void *bits, int size)
{
    Asmbits **pb, *b;
    int i;

    assert(size == 4 || size == 8 || size == 16);
    for (pb=&stash, i=0; (b=*pb); pb=&b->link, i++)
        if (size <= b->size)
        if (memcmp(bits, b->bits, size) == 0)
            return i;
    b = emalloc(sizeof *b);
    memcpy(b->bits, bits, size);
    b->size = size;
    b->link = 0;
    *pb = b;
    return i;
}

void
gasemitfin(FILE *f)
{
    Asmbits *b;
    char *p;
    int sz, i;
    double d;

    if (!stash)
        return;
    fprintf(f, "/* floating point constants */\n.data\n");
    for (sz=16; sz>=4; sz/=2)
        for (b=stash, i=0; b; b=b->link, i++) {
            if (b->size == sz) {
                fprintf(f,
                    ".align %d\n"
                    "%sfp%d:",
                    sz, gasloc, i
                );
                for (p=b->bits; p<&b->bits[sz]; p+=4)
                    fprintf(f, "\n\t.int %"PRId32,
                        *(int32_t *)p);
                if (sz <= 8) {
                    if (sz == 4)
                        d = *(float *)b->bits;
                    else
                        d = *(double *)b->bits;
                    fprintf(f, " /* %f */\n", d);
                } else
                    fprintf(f, "\n");
            }
        }
    while ((b=stash)) {
        stash = b->link;
        free(b);
    }
}