[RFC PATCH 4/6] softfloat: add float*_to_int128 conversion methods

[matheus . ferst]

From: Matheus Ferst <matheus.ferst@eldorado.org.br>

Implements parts_float_to_int2 based on parts_float_to_int logic. The
new methods return the lower part of the result through the "lo"
pointer.

Signed-off-by: Matheus Ferst <matheus.ferst@eldorado.org.br>
---
 fpu/softfloat-parts.c.inc | 75 +++++++++++++++++++++++++++++++++++++++
 fpu/softfloat.c           | 50 ++++++++++++++++++++++++++
 include/fpu/softfloat.h   |  8 +++++
 3 files changed, 133 insertions(+)

diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index 2767aeac03..344df52e5f 100644
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -1096,6 +1096,81 @@ static int64_t partsN(float_to_sint)(FloatPartsN *p, 
FloatRoundMode rmode,
     return r;
 }
 
+static int64_t partsN(float_to_sint2)(FloatPartsN *p, FloatRoundMode rmode,
+                                      int scale, float_status *s, uint64_t *lo)
+{
+    int flags = 0;
+    uint64_t hi;
+
+    switch (p->cls) {
+    case float_class_snan:
+        flags |= float_flag_invalid_snan;
+        /* fall through */
+    case float_class_qnan:
+        flags |= float_flag_invalid;
+        hi = UINT64_MAX;
+        *lo = UINT64_MAX;
+        break;
+
+    case float_class_inf:
+        flags = float_flag_invalid | float_flag_invalid_cvti;
+        if (p->sign) {
+            hi = INT64_MIN;
+            *lo = 0;
+        } else {
+            hi = INT64_MAX;
+            *lo = UINT64_MAX;
+        }
+        break;
+
+    case float_class_zero:
+        *lo = 0;
+        return 0;
+
+    case float_class_normal:
+        if (parts_round_to_int_normal(p, rmode, scale, N - 2)) {
+            flags = float_flag_inexact;
+        }
+
+        if (p->exp <= DECOMPOSED_BINARY_POINT) {
+            hi = 0;
+            *lo = p->frac_hi >> (DECOMPOSED_BINARY_POINT - p->exp);
+        } else if (p->exp <= 127) {
+            int shift = 127 - p->exp;
+            hi = shr_double(0, p->frac_hi, shift);
+            if (N > 64) {
+                *lo = shr_double(p->frac_hi, p->frac_lo, shift);
+            } else {
+                *lo = shr_double(p->frac_hi, 0, shift);
+            }
+        } else {
+            hi = UINT64_MAX;
+            *lo = UINT64_MAX;
+        }
+        if (p->sign) {
+            if (hi < INT64_MIN || (hi == INT64_MIN && *lo == 0)) {
+                *lo = -*lo;
+                hi = ~hi + !*lo;
+            } else {
+                flags = float_flag_invalid | float_flag_invalid_cvti;
+                hi = INT64_MIN;
+                *lo = 0;
+            }
+        } else if (hi > INT64_MAX) {
+            flags = float_flag_invalid | float_flag_invalid_cvti;
+            hi = INT64_MAX;
+            *lo = UINT64_MAX;
+        }
+        break;
+
+    default:
+        g_assert_not_reached();
+    }
+
+    float_raise(flags, s);
+    return hi;
+}
+
 /*
  *  Returns the result of converting the floating-point value `a' to
  *  the unsigned integer format. The conversion is performed according
diff --git a/fpu/softfloat.c b/fpu/softfloat.c
index fe4320060c..41a18f86df 100644
--- a/fpu/softfloat.c
+++ b/fpu/softfloat.c
@@ -840,6 +840,15 @@ static int64_t parts128_float_to_sint(FloatParts128 *p, 
FloatRoundMode rmode,
 #define parts_float_to_sint(P, R, Z, MN, MX, S) \
     PARTS_GENERIC_64_128(float_to_sint, P)(P, R, Z, MN, MX, S)
 
+static int64_t parts64_float_to_sint2(FloatParts64 *p, FloatRoundMode rmode,
+                                      int scale, float_status *s, uint64_t 
*lo);
+static int64_t parts128_float_to_sint2(FloatParts128 *p, FloatRoundMode rmode,
+                                       int scale, float_status *s,
+                                       uint64_t *lo);
+
+#define parts_float_to_sint2(P, R, Z, S, H) \
+    PARTS_GENERIC_64_128(float_to_sint2, P)(P, R, Z, S, H)
+
 static uint64_t parts64_float_to_uint(FloatParts64 *p, FloatRoundMode rmode,
                                       int scale, uint64_t max,
                                       float_status *s);
@@ -3135,6 +3144,15 @@ int64_t float64_to_int64_scalbn(float64 a, 
FloatRoundMode rmode, int scale,
     return parts_float_to_sint(&p, rmode, scale, INT64_MIN, INT64_MAX, s);
 }
 
+int64_t float64_to_int128_scalbn(float64 a, FloatRoundMode rmode, int scale,
+                                 float_status *s, uint64_t *lo)
+{
+    FloatParts64 p;
+
+    float64_unpack_canonical(&p, a, s);
+    return parts_float_to_sint2(&p, rmode, scale, s, lo);
+}
+
 int16_t bfloat16_to_int16_scalbn(bfloat16 a, FloatRoundMode rmode, int scale,
                                  float_status *s)
 {
@@ -3180,6 +3198,16 @@ 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 int64_t float128_to_int128_scalbn(float128 a, FloatRoundMode rmode,
+                                         int scale, float_status *s,
+                                         uint64_t *lo)
+{
+    FloatParts128 p;
+
+    float128_unpack_canonical(&p, a, s);
+    return parts_float_to_sint2(&p, rmode, scale, s, lo);
+}
+
 static int32_t floatx80_to_int32_scalbn(floatx80 a, FloatRoundMode rmode,
                                         int scale, float_status *s)
 {
@@ -3252,6 +3280,11 @@ int64_t float64_to_int64(float64 a, float_status *s)
     return float64_to_int64_scalbn(a, s->float_rounding_mode, 0, s);
 }
 
+int64_t float64_to_int128(float64 a, float_status *s, uint64_t *lo)
+{
+    return float64_to_int128_scalbn(a, s->float_rounding_mode, 0, s, lo);
+}
+
 int32_t float128_to_int32(float128 a, float_status *s)
 {
     return float128_to_int32_scalbn(a, s->float_rounding_mode, 0, s);
@@ -3262,6 +3295,11 @@ int64_t float128_to_int64(float128 a, float_status *s)
     return float128_to_int64_scalbn(a, s->float_rounding_mode, 0, s);
 }
 
+int64_t float128_to_int128(float128 a, float_status *s, uint64_t *lo)
+{
+    return float128_to_int128_scalbn(a, s->float_rounding_mode, 0, s, lo);
+}
+
 int32_t floatx80_to_int32(floatx80 a, float_status *s)
 {
     return floatx80_to_int32_scalbn(a, s->float_rounding_mode, 0, s);
@@ -3317,6 +3355,12 @@ int64_t float64_to_int64_round_to_zero(float64 a, 
float_status *s)
     return float64_to_int64_scalbn(a, float_round_to_zero, 0, s);
 }
 
+int64_t float64_to_int128_round_to_zero(float64 a, float_status *s,
+                                        uint64_t *lo)
+{
+    return float64_to_int128_scalbn(a, float_round_to_zero, 0, s, lo);
+}
+
 int32_t float128_to_int32_round_to_zero(float128 a, float_status *s)
 {
     return float128_to_int32_scalbn(a, float_round_to_zero, 0, s);
@@ -3327,6 +3371,12 @@ 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);
 }
 
+int64_t float128_to_int128_round_to_zero(float128 a, float_status *s,
+                                         uint64_t *lo)
+{
+    return float128_to_int128_scalbn(a, float_round_to_zero, 0, s, lo);
+}
+
 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 01d8edbc73..8d6d2ee62b 100644
--- a/include/fpu/softfloat.h
+++ b/include/fpu/softfloat.h
@@ -746,14 +746,19 @@ float32 float32_default_nan(float_status *status);
 int16_t float64_to_int16_scalbn(float64, FloatRoundMode, int, float_status *);
 int32_t float64_to_int32_scalbn(float64, FloatRoundMode, int, float_status *);
 int64_t float64_to_int64_scalbn(float64, FloatRoundMode, int, float_status *);
+int64_t float64_to_int128_scalbn(float64, FloatRoundMode, int, float_status *,
+                                 uint64_t *);
 
 int16_t float64_to_int16(float64, float_status *status);
 int32_t float64_to_int32(float64, float_status *status);
 int64_t float64_to_int64(float64, float_status *status);
+int64_t float64_to_int128(float64, float_status *status, uint64_t *lo);
 
 int16_t float64_to_int16_round_to_zero(float64, float_status *status);
 int32_t float64_to_int32_round_to_zero(float64, float_status *status);
 int64_t float64_to_int64_round_to_zero(float64, float_status *status);
+int64_t float64_to_int128_round_to_zero(float64, float_status *status,
+                                        uint64_t *lo);
 
 uint16_t float64_to_uint16_scalbn(float64, FloatRoundMode, int, float_status 
*);
 uint32_t float64_to_uint32_scalbn(float64, FloatRoundMode, int, float_status 
*);
@@ -1213,7 +1218,10 @@ 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);
+int64_t float128_to_int128(float128, float_status *status, uint64_t *lo);
 int64_t float128_to_int64_round_to_zero(float128, float_status *status);
+int64_t float128_to_int128_round_to_zero(float128, float_status *status,
+                                         uint64_t *lo);
 uint64_t float128_to_uint64(float128, float_status *status);
 uint64_t float128_to_uint128(float128, float_status *status, uint64_t *lo);
 uint64_t float128_to_uint64_round_to_zero(float128, float_status *status);
-- 
2.25.1