Libc-498.tar.gz

[apple/libc.git] / gdtoa / _ldbl_util.c

diff --git a/gdtoa/_ldbl_util.c b/gdtoa/_ldbl_util.c
new file mode 100644 (file)
index 0000000..1c55d27
--- /dev/null
+++ b/gdtoa/_ldbl_util.c
@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2004 Apple Computer, Inc. All rights reserved.
+ *
+ * @APPLE_LICENSE_HEADER_START@
+ * 
+ * This file contains Original Code and/or Modifications of Original Code
+ * as defined in and that are subject to the Apple Public Source License
+ * Version 2.0 (the 'License'). You may not use this file except in
+ * compliance with the License. Please obtain a copy of the License at
+ * http:www.opensource.apple.com/apsl/ and read it before using this
+ * file.
+ * 
+ * The Original Code and all software distributed under the License are
+ * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
+ * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
+ * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
+ * Please see the License for the specific language governing rights and
+ * limitations under the License.
+ * 
+ * @APPLE_LICENSE_HEADER_END@
+ */
+
+#include <sys/cdefs.h>
+#include <stdint.h>
+#include <strings.h>
+#include <float.h>
+#include <math.h>
+#include <alloca.h>
+
+#include "fpmath.h"
+
+#define        BITS64          64
+#define        DBL_BIAS        (DBL_MAX_EXP - 1)
+#define        DBL_SUBEXP      (-DBL_BIAS + 1)
+#define        LL_BITS         (8 * sizeof(int64_t))
+#define        LL_HIGHBIT      (1LL << 63)
+
+__private_extern__ void
+_ldbl2array32dd(union IEEEl2bits u, uint32_t *a)
+{
+       int bit, shift, highbit, dexp;
+       uint64_t a64[2];
+       int64_t t64;
+
+       bzero(a64, sizeof(a64));
+
+       switch (__fpclassifyd(u.d[0])) {
+       case FP_NORMAL:
+               a64[1] = (1LL << (LDBL_MANT_DIG - BITS64 - 1));
+               /* drop through */
+       case FP_SUBNORMAL:
+               a64[1] |= ((uint64_t)u.bits.manh >> (BITS64 - LDBL_MANL_SIZE));
+               a64[0] = ((uint64_t)u.bits.manh << LDBL_MANL_SIZE);
+               break;
+       default:
+               goto done;
+       }
+
+       dexp = (int)u.bits.exp - (int)u.bits.exp2;
+       /*
+        * if the tail double is so small to not fit in LDBL_MANT_DIG bits,
+        * then just skip it.
+        */
+       if (dexp >= LDBL_MANT_DIG)
+               goto done;
+
+       switch (__fpclassifyd(u.d[1])) {
+       case FP_NORMAL:
+               bit = LDBL_MANT_DIG - dexp - 1;
+               t64 = (1LL << bit);
+               break;
+       case FP_SUBNORMAL:
+               bit = LDBL_MANT_DIG - (int)u.bits.exp;
+               t64 = 0;
+               break;
+       default:
+               goto done;
+       }
+       shift = LDBL_MANL_SIZE - bit - 1;
+       if (shift >= 0)
+               t64 |= (u.bits.manl >> shift);
+       else
+               t64 |= (u.bits.manl << (-shift));
+       highbit = ((a64[0] & LL_HIGHBIT) != 0);
+       if (u.bits.sign == u.bits.sign2) {
+               a64[0] += t64;
+               if (highbit && !(a64[0] & LL_HIGHBIT))  /* carry */
+                       a64[1]++;
+       } else {
+               a64[0] -= t64;
+               if (!highbit && (a64[0] & LL_HIGHBIT))  /* borrow */
+                       a64[1]--;
+       }
+
+       done:
+       a[0] = (uint32_t)a64[0];
+       a[1] = (uint32_t)(a64[0] >> 32);
+       a[2] = (uint32_t)a64[1];
+       a[3] = (uint32_t)(a64[1] >> 32);
+}