softfloat: Move round_to_int to softfloat-parts.c.inc
At the same time, convert to pointers, split out
parts$N_round_to_int_normal, define a macro for
parts_round_to_int using QEMU_GENERIC.
This necessarily meant some rearrangement to the
rount_to_{,u}int_and_pack routines, so go ahead and
convert to parts_round_to_int_normal, which in turn
allows cleaning up of the raised exception handling.
Reviewed-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
diff --git a/fpu/softfloat-parts.c.inc b/fpu/softfloat-parts.c.inc
index f8165d9..b2c4624 100644
--- a/fpu/softfloat-parts.c.inc
+++ b/fpu/softfloat-parts.c.inc
@@ -594,3 +594,160 @@
a->cls = float_class_inf;
return a;
}
+
+/*
+ * Rounds the floating-point value `a' to an integer, and returns the
+ * result as a floating-point value. The operation is performed
+ * according to the IEC/IEEE Standard for Binary Floating-Point
+ * Arithmetic.
+ *
+ * parts_round_to_int_normal is an internal helper function for
+ * normal numbers only, returning true for inexact but not directly
+ * raising float_flag_inexact.
+ */
+static bool partsN(round_to_int_normal)(FloatPartsN *a, FloatRoundMode rmode,
+ int scale, int frac_size)
+{
+ uint64_t frac_lsb, frac_lsbm1, rnd_even_mask, rnd_mask, inc;
+ int shift_adj;
+
+ scale = MIN(MAX(scale, -0x10000), 0x10000);
+ a->exp += scale;
+
+ if (a->exp < 0) {
+ bool one;
+
+ /* All fractional */
+ switch (rmode) {
+ case float_round_nearest_even:
+ one = false;
+ if (a->exp == -1) {
+ FloatPartsN tmp;
+ /* Shift left one, discarding DECOMPOSED_IMPLICIT_BIT */
+ frac_add(&tmp, a, a);
+ /* Anything remaining means frac > 0.5. */
+ one = !frac_eqz(&tmp);
+ }
+ break;
+ case float_round_ties_away:
+ one = a->exp == -1;
+ break;
+ case float_round_to_zero:
+ one = false;
+ break;
+ case float_round_up:
+ one = !a->sign;
+ break;
+ case float_round_down:
+ one = a->sign;
+ break;
+ case float_round_to_odd:
+ one = true;
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ frac_clear(a);
+ a->exp = 0;
+ if (one) {
+ a->frac_hi = DECOMPOSED_IMPLICIT_BIT;
+ } else {
+ a->cls = float_class_zero;
+ }
+ return true;
+ }
+
+ if (a->exp >= frac_size) {
+ /* All integral */
+ return false;
+ }
+
+ if (N > 64 && a->exp < N - 64) {
+ /*
+ * Rounding is not in the low word -- shift lsb to bit 2,
+ * which leaves room for sticky and rounding bit.
+ */
+ shift_adj = (N - 1) - (a->exp + 2);
+ frac_shrjam(a, shift_adj);
+ frac_lsb = 1 << 2;
+ } else {
+ shift_adj = 0;
+ frac_lsb = DECOMPOSED_IMPLICIT_BIT >> (a->exp & 63);
+ }
+
+ frac_lsbm1 = frac_lsb >> 1;
+ rnd_mask = frac_lsb - 1;
+ rnd_even_mask = rnd_mask | frac_lsb;
+
+ if (!(a->frac_lo & rnd_mask)) {
+ /* Fractional bits already clear, undo the shift above. */
+ frac_shl(a, shift_adj);
+ return false;
+ }
+
+ switch (rmode) {
+ case float_round_nearest_even:
+ inc = ((a->frac_lo & rnd_even_mask) != frac_lsbm1 ? frac_lsbm1 : 0);
+ break;
+ case float_round_ties_away:
+ inc = frac_lsbm1;
+ break;
+ case float_round_to_zero:
+ inc = 0;
+ break;
+ case float_round_up:
+ inc = a->sign ? 0 : rnd_mask;
+ break;
+ case float_round_down:
+ inc = a->sign ? rnd_mask : 0;
+ break;
+ case float_round_to_odd:
+ inc = a->frac_lo & frac_lsb ? 0 : rnd_mask;
+ break;
+ default:
+ g_assert_not_reached();
+ }
+
+ if (shift_adj == 0) {
+ if (frac_addi(a, a, inc)) {
+ frac_shr(a, 1);
+ a->frac_hi |= DECOMPOSED_IMPLICIT_BIT;
+ a->exp++;
+ }
+ a->frac_lo &= ~rnd_mask;
+ } else {
+ frac_addi(a, a, inc);
+ a->frac_lo &= ~rnd_mask;
+ /* Be careful shifting back, not to overflow */
+ frac_shl(a, shift_adj - 1);
+ if (a->frac_hi & DECOMPOSED_IMPLICIT_BIT) {
+ a->exp++;
+ } else {
+ frac_add(a, a, a);
+ }
+ }
+ return true;
+}
+
+static void partsN(round_to_int)(FloatPartsN *a, FloatRoundMode rmode,
+ int scale, float_status *s,
+ const FloatFmt *fmt)
+{
+ switch (a->cls) {
+ case float_class_qnan:
+ case float_class_snan:
+ parts_return_nan(a, s);
+ break;
+ case float_class_zero:
+ case float_class_inf:
+ break;
+ case float_class_normal:
+ if (parts_round_to_int_normal(a, rmode, scale, fmt->frac_size)) {
+ float_raise(float_flag_inexact, s);
+ }
+ break;
+ default:
+ g_assert_not_reached();
+ }
+}
