simplify nan check in sqrt (x86 asm); result of sqrt is never negative

[musl] / src / math / i386 / sqrt.s

diff --git a/src/math/i386/sqrt.s b/src/math/i386/sqrt.s
index c6e5530..1bd3b05 100644 (file)
--- a/src/math/i386/sqrt.s
+++ b/src/math/i386/sqrt.s
@@ -2,4 +2,23 @@
 .type sqrt,@function
 sqrt:  fldl 4(%esp)
        fsqrt
+       fstsw %ax
+       sub $12,%esp
+       fld %st(0)
+       fstpt (%esp)
+       mov (%esp),%ecx
+       and $0x7ff,%ecx
+       cmp $0x400,%ecx
+       jnz 1f
+       mov 8(%esp),%cx
+       inc %cx
+       jo 1f
+       and $0x200,%eax
+       sub $0x100,%eax
+       sub %eax,(%esp)
+       fstp %st(0)
+       fldt (%esp)
+1:     add $12,%esp
+       fstpl 4(%esp)
+       fldl 4(%esp)
        ret