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Re: [PATCH] libm round - fix for 16-bit CPU
- From: Craig Howland <howland at LGSInnovations dot com>
- To: <newlib at sourceware dot org>
- Date: Wed, 20 Jun 2018 12:22:28 -0400
- Subject: Re: [PATCH] libm round - fix for 16-bit CPU
- References: <000301d408b0$61a6e1a0$24f4a4e0$@beniston.com>
On 06/20/2018 12:04 PM, Jon Beniston wrote:
Hi,
The following is a patch for round on 16-bit CPUs to avoid a shift being out
of range:
libm/common/s_round.c (round): Make constant long so shift isn't out of
range on 16-bit CPUs
---
newlib/libm/common/s_round.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/newlib/libm/common/s_round.c b/newlib/libm/common/s_round.c
index 047574a84..f0926d85f 100644
--- a/newlib/libm/common/s_round.c
+++ b/newlib/libm/common/s_round.c
@@ -68,7 +68,7 @@ SEEALSO
msw &= 0x80000000;
if (exponent_less_1023 == -1)
/* Result is +1.0 or -1.0. */
- msw |= (1023 << 20);
+ msw |= (1023L << 20);
lsw = 0;
}
else
Might it be slightly better to use a cast with the type of msw? While it would
probably make no difference on any 16-bit target, it could prevent an
intermediate change to 64 bits instead of 32 on some targets. So
+ msw |= (((__int32_t)1023 << 20);
(Or, better for maintenance, but not as portable with a GCC extension:
+ msw |= (((typeof(msw))1023 << 20);
(There do seem to be multiple uses of typeof already, although the first few I checked are all gated with validity checks. So probably not appropriate as shown here.))
Craig