softfloat: add float128_to_int128

Implements float128_to_int128 based on parts_float_to_int logic.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220330175932.6995-7-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

3 files changed, 68 insertions, 0 deletions

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index ce21b64e4f..5e2cf20448 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -3154,6 +3154,60 @@ static int64_t float128_to_int64_scalbn(float128 a, FloatRoundMode rmode,
     return parts_float_to_sint(&p, rmode, scale, INT64_MIN, INT64_MAX, s);
 }
 
+static Int128 float128_to_int128_scalbn(float128 a, FloatRoundMode rmode,
+                                        int scale, float_status *s)
+{
+    int flags = 0;
+    Int128 r;
+    FloatParts128 p;
+
+    float128_unpack_canonical(&p, a, s);
+
+    switch (p.cls) {
+    case float_class_snan:
+        flags |= float_flag_invalid_snan;
+        /* fall through */
+    case float_class_qnan:
+        flags |= float_flag_invalid;
+        r = UINT128_MAX;
+        break;
+
+    case float_class_inf:
+        flags = float_flag_invalid | float_flag_invalid_cvti;
+        r = p.sign ? INT128_MIN : INT128_MAX;
+        break;
+
+    case float_class_zero:
+        return int128_zero();
+
+    case float_class_normal:
+        if (parts_round_to_int_normal(&p, rmode, scale, 128 - 2)) {
+            flags = float_flag_inexact;
+        }
+
+        if (p.exp < 127) {
+            int shift = 127 - p.exp;
+            r = int128_urshift(int128_make128(p.frac_lo, p.frac_hi), shift);
+            if (p.sign) {
+                r = int128_neg(r);
+            }
+        } else if (p.exp == 127 && p.sign && p.frac_lo == 0 &&
+                   p.frac_hi == DECOMPOSED_IMPLICIT_BIT) {
+            r = INT128_MIN;
+        } else {
+            flags = float_flag_invalid | float_flag_invalid_cvti;
+            r = p.sign ? INT128_MIN : INT128_MAX;
+        }
+        break;
+
+    default:
+        g_assert_not_reached();
+    }
+
+    float_raise(flags, s);
+    return r;
+}
+
 static int32_t floatx80_to_int32_scalbn(floatx80 a, FloatRoundMode rmode,
                                         int scale, float_status *s)
 {
@@ -3236,6 +3290,11 @@ int64_t float128_to_int64(float128 a, float_status *s)
     return float128_to_int64_scalbn(a, s->float_rounding_mode, 0, s);
 }
 
+Int128 float128_to_int128(float128 a, float_status *s)
+{
+    return float128_to_int128_scalbn(a, s->float_rounding_mode, 0, s);
+}
+
 int32_t floatx80_to_int32(floatx80 a, float_status *s)
 {
     return floatx80_to_int32_scalbn(a, s->float_rounding_mode, 0, s);
@@ -3301,6 +3360,11 @@ int64_t float128_to_int64_round_to_zero(float128 a, float_status *s)
     return float128_to_int64_scalbn(a, float_round_to_zero, 0, s);
 }
 
+Int128 float128_to_int128_round_to_zero(float128 a, float_status *s)
+{
+    return float128_to_int128_scalbn(a, float_round_to_zero, 0, s);
+}
+
 int32_t floatx80_to_int32_round_to_zero(floatx80 a, float_status *s)
 {
     return floatx80_to_int32_scalbn(a, float_round_to_zero, 0, s);
diff --git a/include/fpu/softfloat.h b/include/fpu/softfloat.h
index 6cfe9ee474..3dcf20e3a2 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -1204,7 +1204,9 @@ floatx80 floatx80_default_nan(float_status *status);
 int32_t float128_to_int32(float128, float_status *status);
 int32_t float128_to_int32_round_to_zero(float128, float_status *status);
 int64_t float128_to_int64(float128, float_status *status);
+Int128 float128_to_int128(float128, float_status *status);
 int64_t float128_to_int64_round_to_zero(float128, float_status *status);
+Int128 float128_to_int128_round_to_zero(float128, float_status *status);
 uint64_t float128_to_uint64(float128, float_status *status);
 Int128 float128_to_uint128(float128, float_status *status);
 uint64_t float128_to_uint64_round_to_zero(float128, float_status *status);
diff --git a/include/qemu/int128.h b/include/qemu/int128.h
index 1f82918c73..ef71f56e3f 100644
--- a/include/qemu/int128.h
+++ b/include/qemu/int128.h
@@ -431,5 +431,7 @@ static inline void bswap128s(Int128 *s)
 }
 
 #define UINT128_MAX int128_make128(~0LL, ~0LL)
+#define INT128_MAX int128_make128(UINT64_MAX, INT64_MAX)
+#define INT128_MIN int128_make128(0, INT64_MIN)
 
 #endif /* INT128_H */