softfloat: add uint128_to_float128

Based on parts_uint_to_float, implements uint128_to_float128 to convert
an unsigned 128-bit value received through an Int128 argument.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20220330175932.6995-4-matheus.ferst@eldorado.org.br>
Signed-off-by: Daniel Henrique Barboza <danielhb413@gmail.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index 7f524d4377..57445b36e7 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -3969,6 +3969,31 @@ float128 uint64_to_float128(uint64_t a, float_status *status)
     return float128_round_pack_canonical(&p, status);
 }
 
+float128 uint128_to_float128(Int128 a, float_status *status)
+{
+    FloatParts128 p = { };
+    int shift;
+
+    if (int128_nz(a)) {
+        p.cls = float_class_normal;
+
+        shift = clz64(int128_gethi(a));
+        if (shift == 64) {
+            shift += clz64(int128_getlo(a));
+        }
+
+        p.exp = 127 - shift;
+        a = int128_lshift(a, shift);
+
+        p.frac_hi = int128_gethi(a);
+        p.frac_lo = int128_getlo(a);
+    } else {
+        p.cls = float_class_zero;
+    }
+
+    return float128_round_pack_canonical(&p, status);
+}
+
 /*
  * Minimum and maximum
  */