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Prevent silent overflow of mantissa 

When converting a binary constant to a real value in the vvp code
generator, make sure the mantissa does not overflow. If it does,
panic in some way.
This commit is contained in:
Stephen Williams 2008-08-16 18:30:07 -07:00
parent f8bd8e1bd6
commit 66bed241f1
1 changed files with 14 additions and 3 deletions
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17
tgt-vvp/eval_real.c
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@ -168,12 +168,23 @@ static int draw_number_real(ivl_expr_t exp)
unsigned long mant = 0, mask = -1UL;
int vexp = 0x1000;
for (idx = 0 ; idx < wid ; idx += 1) {
for (idx = 0 ; idx < wid && idx < 8*sizeof(mant) ; idx += 1) {
mask <<= 1;
if (bits[idx] == '1')
mant |= 1 << idx;
}
for ( ; idx < wid ; idx += 1) {
if (ivl_expr_signed(exp) && (bits[idx] == bits[8*sizeof(mant)-1]))
continue;
if (bits[idx] == '0')
continue;
fprintf(stderr, "internal error: mantissa doesn't fit!\n");
assert(0);
}
/* If this is actually a negative number, then get the
positive equivalent, and set the sign bit in the exponent
field.
@ -188,8 +199,8 @@ static int draw_number_real(ivl_expr_t exp)
vexp |= 0x4000;
}
fprintf(vvp_out, " %%loadi/wr %d, %lu, %d; load(num)= %c%lu\n",
res, mant, vexp, (vexp&0x4000)? '-' : '+', mant);
fprintf(vvp_out, " %%loadi/wr %d, %lu, %d; load(num)= %c%lu (wid=%u)\n",
res, mant, vexp, (vexp&0x4000)? '-' : '+', mant, wid);
return res;
}