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Re: [RFC/PATCH] Enable IEEE_Arith when double is 32 bits for strtod


Patch applied. Thanks.

-- Jeff J.

Antony KING wrote:
Hi,

Attached is a 2 part patch I have constructed against 1.15.0 of newlib
in which part 1 fixes some compilation errors detected as a result of
defining "IEEE_Arith" in part 2 of the patch.

The second part of the patch fixes an error detected by Plumhall C test
suite (2007A) when running an application where doubles are 32 bits (in
this instance with the GCC SH4 ABI -m4-single-only). The test suite is
expecting that +/- HUGE_VAL is returned on overflow, which is the case
when a double is 64 bits but not when 32 bits. Part 2 of the patch
enables this behaviour. I also have attached a reduced form of the test
which illustrates the failure.

The ChangeLog entry:

        * libc/stdlib/mprec.h [_DOUBLE_IS_32BITS}: Define IEEE_Arith
	bits and redefine associated dword0 macro (rvalue issue).
	* libc/stdio/vfieeefp.h: Ditto.
        * libc/stdlib/strtod.c: Add checks for _DOUBLE_IS_32BITS
        to prevent setting dword1 which is an rvalue only.

Cheers,

Antony.



------------------------------------------------------------------------

--- newlib/libc/stdio/vfieeefp.h@@/NEWLIB-1.15.0	2004-05-26 01:19:14.000000000 +0100
+++ newlib/libc/stdio/vfieeefp.h	2007-08-17 18:13:46.259368000 +0100
@@ -170,9 +170,7 @@
 #define Exp_mask    ((__uint32_t)0x7f800000L)
 #define P    	    24
 #define Bias 	    127
-#if 0
-#define IEEE_Arith  /* it is, but the code doesn't handle IEEE singles yet */
-#endif
+#define IEEE_Arith
 #define Emin        (-126)
 #define Exp_1       ((__uint32_t)0x3f800000L)
 #define Exp_11      ((__uint32_t)0x3f800000L)
--- newlib/libc/stdlib/mprec.h.orig	2007-08-28 11:41:24.994483000 +0100
+++ newlib/libc/stdlib/mprec.h	2007-08-17 18:56:06.969216000 +0100
@@ -139,15 +139,7 @@
 #define P    	    24
 #define Bias 	    127
 #define NO_HEX_FP   /* not supported in this case */
-#if 0
-#define IEEE_Arith  /* it is, but the code doesn't handle IEEE singles yet */
-#endif
-/* Following is needed due to IEEE_Arith not being set on above.  */
-#if defined(__v800)
-#define n_bigtens 2
-#else
-#define n_bigtens 5
-#endif
+#define IEEE_Arith
 #define Emin        (-126)
 #define Exp_1       ((__uint32_t)0x3f800000L)
 #define Exp_11      ((__uint32_t)0x3f800000L)


------------------------------------------------------------------------


--- newlib/libc/stdlib/mprec.h@@/NEWLIB-1.15.0 2006-07-05 17:18:30.000000000 +0100
+++ newlib/libc/stdlib/mprec.h 2007-08-28 11:41:24.994483000 +0100
@@ -175,7 +175,11 @@
#define word0(x) (x.i[0])
#define word1(x) 0
+#ifdef YES_ALIAS
#define dword0(x) ((__ULong *)&x)[0]
+#else
+#define dword0(x) ((U*)&x)->L[0]
+#endif
#define dword1(x) 0
#else
--- newlib/libc/stdlib/strtod.c@@/NEWLIB-1.15.0 2006-07-05 17:18:30.000000000 +0100
+++ newlib/libc/stdlib/strtod.c 2007-08-17 19:11:58.711787000 +0100
@@ -386,7 +386,9 @@
if (!match(&s,"inity"))
++s;
dword0(rv) = 0x7ff00000;
+#ifndef _DOUBLE_IS_32BITS
dword1(rv) = 0;
+#endif /*!_DOUBLE_IS_32BITS*/
goto ret;
}
break;
@@ -398,12 +400,16 @@
&& hexnan(&s, &fpinan, bits)
== STRTOG_NaNbits) {
dword0(rv) = 0x7ff00000 | bits[1];
+#ifndef _DOUBLE_IS_32BITS
dword1(rv) = bits[0];
+#endif /*!_DOUBLE_IS_32BITS*/
}
else {
#endif
dword0(rv) = NAN_WORD0;
+#ifndef _DOUBLE_IS_32BITS
dword1(rv) = NAN_WORD1;
+#endif /*!_DOUBLE_IS_32BITS*/
#ifndef No_Hex_NaN
}
#endif
@@ -627,8 +633,8 @@
#ifndef _DOUBLE_IS_32BITS
else
dword1(rv) &= 0xffffffff << j;
- }
#endif /*!_DOUBLE_IS_32BITS*/
+ }
#else
for(j = 0; e1 > 1; j++, e1 >>= 1)
if (e1 & 1)
@@ -1109,7 +1115,9 @@
if (inexact) {
if (!oldinexact) {
dword0(rv0) = Exp_1 + (70 << Exp_shift);
+#ifndef _DOUBLE_IS_32BITS
dword1(rv0) = 0;
+#endif /*!_DOUBLE_IS_32BITS*/
dval(rv0) += 1.;
}
}
@@ -1119,7 +1127,9 @@
#ifdef Avoid_Underflow
if (scale) {
dword0(rv0) = Exp_1 - 2*P*Exp_msk1;
+#ifndef _DOUBLE_IS_32BITS
dword1(rv0) = 0;
+#endif /*!_DOUBLE_IS_32BITS*/
dval(rv) *= dval(rv0);
#ifndef NO_ERRNO
/* try to avoid the bug of testing an 8087 register value */



------------------------------------------------------------------------


#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <stdlib.h>

static int deq(double val1, double val2)
{
if (val1 != val2) {
printf("got %f, expected %f\n", val1, val2);
}
}


static int ieq(int val1, int val2)
{
if (val1 != val2) {
printf("got %d, expected %d\n", val1, val2);
}
}


int main(void)
{
/* overflow returns +/- HUGE_VAL */
errno = 0;
deq(strtod("2.3e99999999999999999999", NULL), HUGE_VAL);
ieq(errno, ERANGE);
errno = 0;
deq(strtod("-1e99999999999999999999", NULL), -HUGE_VAL);
ieq(errno, ERANGE);


  return 0;
}


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