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authorRich Felker <dalias@aerifal.cx>2018-06-14 11:00:58 -0400
committerRich Felker <dalias@aerifal.cx>2018-06-14 13:59:41 -0400
commit18f02c42a2b5397e8541f4663eb6ca00c1a806dd (patch)
tree88299f2477ca68b54ef6a5b5051bb56b79a51d9d
parentd5e55ba3320c30310ca1d8938925d5424a652422 (diff)
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add support for m68k 80-bit long double variant
since x86 and m68k are the only archs with 80-bit long double and each has mandatory endianness, select the variant via endianness. differences are minor: apparently just byte order and representation of infinities. the m68k format is not well-documented anywhere I could find, so if other differences are found they may require additional changes later.
-rw-r--r--src/internal/libm.h11
-rw-r--r--src/math/__fpclassifyl.c12
2 files changed, 21 insertions, 2 deletions
diff --git a/src/internal/libm.h b/src/internal/libm.h
index df864111..a2505f7e 100644
--- a/src/internal/libm.h
+++ b/src/internal/libm.h
@@ -28,6 +28,17 @@ union ldshape {
uint16_t se;
} i;
};
+#elif LDBL_MANT_DIG == 64 && LDBL_MAX_EXP == 16384 && __BYTE_ORDER == __BIG_ENDIAN
+/* This is the m68k variant of 80-bit long double, and this definition only works
+ * on archs where the alignment requirement of uint64_t is <= 4. */
+union ldshape {
+ long double f;
+ struct {
+ uint16_t se;
+ uint16_t pad;
+ uint64_t m;
+ } i;
+};
#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384 && __BYTE_ORDER == __LITTLE_ENDIAN
union ldshape {
long double f;
diff --git a/src/math/__fpclassifyl.c b/src/math/__fpclassifyl.c
index 481c0b94..e41781b6 100644
--- a/src/math/__fpclassifyl.c
+++ b/src/math/__fpclassifyl.c
@@ -13,10 +13,18 @@ int __fpclassifyl(long double x)
int msb = u.i.m>>63;
if (!e && !msb)
return u.i.m ? FP_SUBNORMAL : FP_ZERO;
+ if (e == 0x7fff) {
+ /* The x86 variant of 80-bit extended precision only admits
+ * one representation of each infinity, with the mantissa msb
+ * necessarily set. The version with it clear is invalid/nan.
+ * The m68k variant, however, allows either, and tooling uses
+ * the version with it clear. */
+ if (__BYTE_ORDER == __LITTLE_ENDIAN && !msb)
+ return FP_NAN;
+ return u.i.m << 1 ? FP_NAN : FP_INFINITE;
+ }
if (!msb)
return FP_NAN;
- if (e == 0x7fff)
- return u.i.m << 1 ? FP_NAN : FP_INFINITE;
return FP_NORMAL;
}
#elif LDBL_MANT_DIG == 113 && LDBL_MAX_EXP == 16384