softfloat: Add float to 16bit integer conversions.

ARMv8 requires support for converting 32 and 64bit floating point
values to signed and unsigned 16bit integers.
Signed-off-by: NWill Newton <will.newton@linaro.org>
[PMM: updated not to incorrectly set Inexact for Invalid inputs]
Signed-off-by: NPeter Maydell <peter.maydell@linaro.org>
Reviewed-by: NRichard Henderson <rth@twiddle.net>

fpu/softfloat.c

@@ -6491,6 +6491,46 @@ uint32 float32_to_uint32_round_to_zero( float32 a STATUS_PARAM )
     return res;
 }
 
+int_fast16_t float32_to_int16(float32 a STATUS_PARAM)
+{
+    int32_t v;
+    int_fast16_t res;
+    int old_exc_flags = get_float_exception_flags(status);
+
+    v = float32_to_int32(a STATUS_VAR);
+    if (v < -0x8000) {
+        res = -0x8000;
+    } else if (v > 0x7fff) {
+        res = 0x7fff;
+    } else {
+        return v;
+    }
+
+    set_float_exception_flags(old_exc_flags, status);
+    float_raise(float_flag_invalid STATUS_VAR);
+    return res;
+}
+
+uint_fast16_t float32_to_uint16(float32 a STATUS_PARAM)
+{
+    int32_t v;
+    uint_fast16_t res;
+    int old_exc_flags = get_float_exception_flags(status);
+
+    v = float32_to_int32(a STATUS_VAR);
+    if (v < 0) {
+        res = 0;
+    } else if (v > 0xffff) {
+        res = 0xffff;
+    } else {
+        return v;
+    }
+
+    set_float_exception_flags(old_exc_flags, status);
+    float_raise(float_flag_invalid STATUS_VAR);
+    return res;
+}
+
 uint_fast16_t float32_to_uint16_round_to_zero(float32 a STATUS_PARAM)
 {
     int64_t v;
@@ -6545,6 +6585,46 @@ uint32 float64_to_uint32_round_to_zero( float64 a STATUS_PARAM )
     return res;
 }
 
+int_fast16_t float64_to_int16(float64 a STATUS_PARAM)
+{
+    int64_t v;
+    int_fast16_t res;
+    int old_exc_flags = get_float_exception_flags(status);
+
+    v = float64_to_int32(a STATUS_VAR);
+    if (v < -0x8000) {
+        res = -0x8000;
+    } else if (v > 0x7fff) {
+        res = 0x7fff;
+    } else {
+        return v;
+    }
+
+    set_float_exception_flags(old_exc_flags, status);
+    float_raise(float_flag_invalid STATUS_VAR);
+    return res;
+}
+
+uint_fast16_t float64_to_uint16(float64 a STATUS_PARAM)
+{
+    int64_t v;
+    uint_fast16_t res;
+    int old_exc_flags = get_float_exception_flags(status);
+
+    v = float64_to_int32(a STATUS_VAR);
+    if (v < 0) {
+        res = 0;
+    } else if (v > 0xffff) {
+        res = 0xffff;
+    } else {
+        return v;
+    }
+
+    set_float_exception_flags(old_exc_flags, status);
+    float_raise(float_flag_invalid STATUS_VAR);
+    return res;
+}
+
 uint_fast16_t float64_to_uint16_round_to_zero(float64 a STATUS_PARAM)
 {
     int64_t v;

include/fpu/softfloat.h

@@ -265,6 +265,8 @@ extern const float16 float16_default_nan;
 /*----------------------------------------------------------------------------
 | Software IEC/IEEE single-precision conversion routines.
 *----------------------------------------------------------------------------*/
+int_fast16_t float32_to_int16(float32 STATUS_PARAM);
+uint_fast16_t float32_to_uint16(float32 STATUS_PARAM);
 int_fast16_t float32_to_int16_round_to_zero(float32 STATUS_PARAM);
 uint_fast16_t float32_to_uint16_round_to_zero(float32 STATUS_PARAM);
 int32 float32_to_int32( float32 STATUS_PARAM );
@@ -371,6 +373,8 @@ extern const float32 float32_default_nan;
 /*----------------------------------------------------------------------------
 | Software IEC/IEEE double-precision conversion routines.
 *----------------------------------------------------------------------------*/
+int_fast16_t float64_to_int16(float64 STATUS_PARAM);
+uint_fast16_t float64_to_uint16(float64 STATUS_PARAM);
 int_fast16_t float64_to_int16_round_to_zero(float64 STATUS_PARAM);
 uint_fast16_t float64_to_uint16_round_to_zero(float64 STATUS_PARAM);
 int32 float64_to_int32( float64 STATUS_PARAM );