sf: add f16_to_[u]i16

use f16_to_[u]i]3 and handle overflow and underflow range for 16bit
integer

Signed-off-by: Chih-Min Chao <chihmin.chao@sifive.com>

5 files changed, 209 insertions, 0 deletions

diff --git a/softfloat/f16_to_i16.c b/softfloat/f16_to_i16.c
new file mode 100644
index 0000000..b05cd8c
--- /dev/null
+++ b/softfloat/f16_to_i16.c
@@ -0,0 +1,101 @@
+
+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3d, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017 The Regents of the
+University of California.  All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice,
+    this list of conditions, and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions, and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ 3. Neither the name of the University nor the names of its contributors may
+    be used to endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
+DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+=============================================================================*/
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "internals.h"
+#include "specialize.h"
+#include "softfloat.h"
+
+int_fast16_t f16_to_i16( float16_t a, uint_fast8_t roundingMode, bool exact )
+{
+    union ui16_f16 uA;
+    uint_fast16_t uiA;
+    bool sign;
+    int_fast8_t exp;
+    uint_fast16_t frac;
+    int_fast32_t sig32;
+    int_fast8_t shiftDist;
+    bool do_round = true;
+
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    uA.f = a;
+    uiA = uA.ui;
+    sign = signF16UI( uiA );
+    exp  = expF16UI( uiA );
+    frac = fracF16UI( uiA );
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    if ( exp == 0x1F ) {
+        softfloat_raiseFlags( softfloat_flag_invalid );
+        return
+            frac ? i16_fromNaN
+                : sign ? i16_fromNegOverflow : i16_fromPosOverflow;
+    }
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    sig32 = frac;
+    if ( exp ) {
+        sig32 |= 0x0400;
+        shiftDist = exp - 0x19;
+        if ( 0 <= shiftDist ) {
+            sig32 <<= shiftDist;
+            sig32 = sign ? -sig32 : sig32;
+            do_round = false;
+        } else {
+          shiftDist = exp - 0x0D;
+          if ( 0 < shiftDist )
+              sig32 <<= shiftDist;
+        }
+    }
+
+    if (do_round)
+        sig32 = softfloat_roundToI32(
+                  sign, (uint_fast32_t) sig32, roundingMode, exact);
+
+    if (sig32 > INT16_MAX) {
+        softfloat_exceptionFlags |= softfloat_flag_invalid;
+        return i16_fromPosOverflow;
+    } else if (sig32 < INT16_MIN) {
+        softfloat_exceptionFlags |= softfloat_flag_invalid;
+        return i16_fromNegOverflow;
+    } else {
+        return sig32;
+    }
+}
+
diff --git a/softfloat/f16_to_ui16.c b/softfloat/f16_to_ui16.c
new file mode 100644
index 0000000..652daff
--- /dev/null
+++ b/softfloat/f16_to_ui16.c
@@ -0,0 +1,97 @@
+
+/*============================================================================
+
+This C source file is part of the SoftFloat IEEE Floating-Point Arithmetic
+Package, Release 3d, by John R. Hauser.
+
+Copyright 2011, 2012, 2013, 2014, 2015, 2016, 2017 The Regents of the
+University of California.  All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice,
+    this list of conditions, and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions, and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ 3. Neither the name of the University nor the names of its contributors may
+    be used to endorse or promote products derived from this software without
+    specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS "AS IS", AND ANY
+EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE, ARE
+DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
+DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
+(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
+LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
+ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+
+=============================================================================*/
+
+#include <stdbool.h>
+#include <stdint.h>
+#include "platform.h"
+#include "internals.h"
+#include "specialize.h"
+#include "softfloat.h"
+
+uint_fast16_t f16_to_ui16( float16_t a, uint_fast8_t roundingMode, bool exact )
+{
+    union ui16_f16 uA;
+    uint_fast16_t uiA;
+    bool sign;
+    int_fast8_t exp;
+    uint_fast16_t frac;
+    uint_fast32_t sig32;
+    int_fast8_t shiftDist;
+    bool do_round = true;
+
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    uA.f = a;
+    uiA = uA.ui;
+    sign = signF16UI( uiA );
+    exp  = expF16UI( uiA );
+    frac = fracF16UI( uiA );
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    if ( exp == 0x1F ) {
+        softfloat_raiseFlags( softfloat_flag_invalid );
+        return
+            frac ? ui16_fromNaN
+                : sign ? ui16_fromNegOverflow : ui16_fromPosOverflow;
+    }
+    /*------------------------------------------------------------------------
+    *------------------------------------------------------------------------*/
+    sig32 = frac;
+    if ( exp ) {
+        sig32 |= 0x0400;
+        shiftDist = exp - 0x19;
+        if ( (0 <= shiftDist) && !sign ) {
+           sig32 << shiftDist;
+           do_round = false;
+        } else {
+            shiftDist = exp - 0x0D;
+            if ( 0 < shiftDist )
+                sig32 <<= shiftDist;
+        }
+    }
+
+    if (do_round)
+        sig32 = softfloat_roundToUI32( sign, sig32, roundingMode, exact );
+
+    if (sig32 > UINT16_MAX) {
+        softfloat_exceptionFlags |= softfloat_flag_invalid;
+        return ui16_fromPosOverflow;
+    } else {
+        return sig32;
+    }
+
+}
+
diff --git a/softfloat/softfloat.h b/softfloat/softfloat.h
index 540d2fb..c93c3c5 100644
--- a/softfloat/softfloat.h
+++ b/softfloat/softfloat.h
@@ -141,8 +141,10 @@ void i64_to_f128M( int64_t, float128_t * );
 /*----------------------------------------------------------------------------
 | 16-bit (half-precision) floating-point operations.
 *----------------------------------------------------------------------------*/
+uint_fast16_t f16_to_ui16( float16_t, uint_fast8_t, bool );
 uint_fast32_t f16_to_ui32( float16_t, uint_fast8_t, bool );
 uint_fast64_t f16_to_ui64( float16_t, uint_fast8_t, bool );
+int_fast16_t f16_to_i16( float16_t, uint_fast8_t, bool );
 int_fast32_t f16_to_i32( float16_t, uint_fast8_t, bool );
 int_fast64_t f16_to_i64( float16_t, uint_fast8_t, bool );
 uint_fast32_t f16_to_ui32_r_minMag( float16_t, bool );
diff --git a/softfloat/softfloat.mk.in b/softfloat/softfloat.mk.in
index 0ca17cd..90ce30c 100644
--- a/softfloat/softfloat.mk.in
+++ b/softfloat/softfloat.mk.in
@@ -56,10 +56,12 @@ softfloat_c_srcs = \
 	f16_to_f128.c \
 	f16_to_f32.c \
 	f16_to_f64.c \
+	f16_to_i16.c \
 	f16_to_i32.c \
 	f16_to_i32_r_minMag.c \
 	f16_to_i64.c \
 	f16_to_i64_r_minMag.c \
+	f16_to_ui16.c \
 	f16_to_ui32.c \
 	f16_to_ui32_r_minMag.c \
 	f16_to_ui64.c \
diff --git a/softfloat/specialize.h b/softfloat/specialize.h
index 629d518..8bd9857 100644
--- a/softfloat/specialize.h
+++ b/softfloat/specialize.h
@@ -55,6 +55,13 @@ extern "C" {
 | The values to return on conversions to 32-bit integer formats that raise an
 | invalid exception.
 *----------------------------------------------------------------------------*/
+#define ui16_fromPosOverflow 0xFFFF
+#define ui16_fromNegOverflow 0
+#define ui16_fromNaN         0xFFFF
+#define i16_fromPosOverflow  0x7FFF
+#define i16_fromNegOverflow  (-0x7FFF - 1)
+#define i16_fromNaN          0x7FFF
+
 #define ui32_fromPosOverflow 0xFFFFFFFF
 #define ui32_fromNegOverflow 0
 #define ui32_fromNaN         0xFFFFFFFF