math: fix i386 atan2.s to raise underflow for subnormal results

diff --git a/src/math/i386/atan2.s b/src/math/i386/atan2.s
index 5c795af..a7d2979 100644 (file)
--- a/src/math/i386/atan2.s
+++ b/src/math/i386/atan2.s
@@ -4,4 +4,14 @@ atan2:
        fldl 4(%esp)
        fldl 12(%esp)
        fpatan
-       ret
+       fstl 4(%esp)
+       mov 8(%esp),%eax
+       add %eax,%eax
+       cmp $0x00200000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+       fnstsw %ax
+       and $16,%ax
+       jnz 1f
+       fsts 4(%esp)
+1:     ret

diff --git a/src/math/i386/atan2f.s b/src/math/i386/atan2f.s
index 08627e6..14b88ce 100644 (file)
--- a/src/math/i386/atan2f.s
+++ b/src/math/i386/atan2f.s
@@ -4,4 +4,16 @@ atan2f:
        flds 4(%esp)
        flds 8(%esp)
        fpatan
-       ret
+       fsts 4(%esp)
+       mov 4(%esp),%eax
+       add %eax,%eax
+       cmp $0x01000000,%eax
+       jae 1f
+               # subnormal x, return x with underflow
+       fnstsw %ax
+       and $16,%ax
+       jnz 1f
+       fld %st(0)
+       fmul %st(1)
+       fstps 4(%esp)
+1:     ret