aboutsummaryrefslogtreecommitdiff
path: root/source/f32_rem.c
diff options
context:
space:
mode:
authorJohn Hauser <jhauser@eecs.berkeley.edu>2014-11-28 19:49:28 -0800
committerJohn Hauser <jhauser@eecs.berkeley.edu>2014-11-28 19:49:28 -0800
commit8f59d925353145a65c09301dea6c47da1f1311b1 (patch)
treec55a81490cc411be6c812a5bfcc8fdc48296def9 /source/f32_rem.c
downloadberkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.zip
berkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.tar.gz
berkeley-softfloat-3-8f59d925353145a65c09301dea6c47da1f1311b1.tar.bz2
First draft of RC for Release 3, to start review process.
Diffstat (limited to 'source/f32_rem.c')
-rw-r--r--source/f32_rem.c167
1 files changed, 167 insertions, 0 deletions
diff --git a/source/f32_rem.c b/source/f32_rem.c
new file mode 100644
index 0000000..73bcb00
--- /dev/null
+++ b/source/f32_rem.c
@@ -0,0 +1,167 @@
+
+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014 The Regents of the University of California
+(Regents). All Rights Reserved. Redistribution and use in source and binary
+forms, with or without modification, are permitted provided that the following
+conditions are met:
+
+Redistributions of source code must retain the above copyright notice,
+this list of conditions, and the following two paragraphs of disclaimer.
+Redistributions in binary form must reproduce the above copyright notice,
+this list of conditions, and the following two paragraphs of disclaimer in the
+documentation and/or other materials provided with the distribution. Neither
+the name of the Regents nor the names of its contributors may be used to
+endorse or promote products derived from this software without specific prior
+written permission.
+
+IN NO EVENT SHALL REGENTS BE LIABLE TO ANY PARTY FOR DIRECT, INDIRECT,
+SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES, INCLUDING LOST PROFITS, ARISING
+OUT OF THE USE OF THIS SOFTWARE AND ITS DOCUMENTATION, EVEN IF REGENTS HAS
+BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+REGENTS SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING, BUT NOT LIMITED
+TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
+PURPOSE. THE SOFTWARE AND ACCOMPANYING DOCUMENTATION, IF ANY, PROVIDED
+HEREUNDER IS PROVIDED "AS IS". REGENTS HAS NO OBLIGATION TO PROVIDE
+MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
+
+=============================================================================*/
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "internals.h"
+#include "specialize.h"
+#include "softfloat.h"
+
+float32_t f32_rem( float32_t a, float32_t b )
+{
+ union ui32_f32 uA;
+ uint_fast32_t uiA;
+ bool signA;
+ int_fast16_t expA;
+ uint_fast32_t sigA;
+ union ui32_f32 uB;
+ uint_fast32_t uiB;
+ int_fast16_t expB;
+ uint_fast32_t sigB;
+ struct exp16_sig32 normExpSig;
+ uint_fast32_t rem;
+ int_fast16_t expDiff;
+ uint32_t q, recip32;
+ uint_fast32_t altRem;
+ uint32_t meanRem;
+ bool signRem;
+ uint_fast32_t uiZ;
+ union ui32_f32 uZ;
+
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ uA.f = a;
+ uiA = uA.ui;
+ signA = signF32UI( uiA );
+ expA = expF32UI( uiA );
+ sigA = fracF32UI( uiA );
+ uB.f = b;
+ uiB = uB.ui;
+ expB = expF32UI( uiB );
+ sigB = fracF32UI( uiB );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ if ( expA == 0xFF ) {
+ if ( sigA || ((expB == 0xFF) && sigB) ) goto propagateNaN;
+ goto invalid;
+ }
+ if ( expB == 0xFF ) {
+ if ( sigB ) goto propagateNaN;
+ return a;
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ if ( ! expB ) {
+ if ( ! sigB ) goto invalid;
+ normExpSig = softfloat_normSubnormalF32Sig( sigB );
+ expB = normExpSig.exp;
+ sigB = normExpSig.sig;
+ }
+ if ( ! expA ) {
+ if ( ! sigA ) return a;
+ normExpSig = softfloat_normSubnormalF32Sig( sigA );
+ expA = normExpSig.exp;
+ sigA = normExpSig.sig;
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ rem = sigA | 0x00800000;
+ sigB |= 0x00800000;
+ expDiff = expA - expB;
+ if ( expDiff < 1 ) {
+ if ( expDiff < -1 ) return a;
+ sigB <<= 6;
+ if ( expDiff ) {
+ rem <<= 5;
+ q = 0;
+ } else {
+ rem <<= 6;
+ q = (sigB <= rem);
+ if ( q ) rem -= sigB;
+ }
+ } else {
+ recip32 = softfloat_approxRecip32_1( sigB<<8 );
+ /*--------------------------------------------------------------------
+ | Changing the shift of `rem' here requires also changing the initial
+ | subtraction from `expDiff'.
+ *--------------------------------------------------------------------*/
+ rem <<= 7;
+ expDiff -= 31;
+ /*--------------------------------------------------------------------
+ | The scale of `sigB' affects how many bits are obtained during each
+ | cycle of the loop. Currently this is 29 bits per loop iteration,
+ | which is believed to be the maximum possible.
+ *--------------------------------------------------------------------*/
+ sigB <<= 6;
+ for (;;) {
+ q = ((uint32_t) rem * (uint_fast64_t) recip32)>>32;
+ if ( expDiff < 0 ) break;
+ rem = -(q * (uint32_t) sigB);
+ expDiff -= 29;
+ }
+ /*--------------------------------------------------------------------
+ | (`expDiff' cannot be less than -30 here.)
+ *--------------------------------------------------------------------*/
+ q >>= ~expDiff & 31;
+ rem = (rem<<(expDiff + 30)) - q * (uint32_t) sigB;
+ }
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ do {
+ altRem = rem;
+ ++q;
+ rem -= sigB;
+ } while ( ! (rem & 0x80000000) );
+ meanRem = rem + altRem;
+ if ( (meanRem & 0x80000000) || (! meanRem && (q & 1)) ) rem = altRem;
+ signRem = signA;
+ if ( 0x80000000 <= rem ) {
+ signRem = ! signRem;
+ rem = -rem;
+ }
+ return softfloat_normRoundPackToF32( signRem, expB, rem );
+ /*------------------------------------------------------------------------
+ *------------------------------------------------------------------------*/
+ propagateNaN:
+ uiZ = softfloat_propagateNaNF32UI( uiA, uiB );
+ goto uiZ;
+ invalid:
+ softfloat_raiseFlags( softfloat_flag_invalid );
+ uiZ = defaultNaNF32UI;
+ uiZ:
+ uZ.ui = uiZ;
+ return uZ.f;
+
+}
+
generated by cgit v1.1 at 2025-03-22 17:49:59 +0000