target-arm: Move arm_rmode_to_sf to a shared location.

This function will be needed for AArch32 ARMv8 support, so move it to
helper.c where it can be used by both targets. Also moves the code out
of line, but as it is quite a large function I don't believe this
should be a significant performance impact.

Signed-off-by: Will Newton <will.newton@linaro.org>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
diff --git a/target-arm/helper.c b/target-arm/helper.c
index c708f15..b1541b9 100644
--- a/target-arm/helper.c
+++ b/target-arm/helper.c
@@ -4418,3 +4418,31 @@
 
     return ret;
 }
+
+/* Convert ARM rounding mode to softfloat */
+int arm_rmode_to_sf(int rmode)
+{
+    switch (rmode) {
+    case FPROUNDING_TIEAWAY:
+        rmode = float_round_ties_away;
+        break;
+    case FPROUNDING_ODD:
+        /* FIXME: add support for TIEAWAY and ODD */
+        qemu_log_mask(LOG_UNIMP, "arm: unimplemented rounding mode: %d\n",
+                      rmode);
+    case FPROUNDING_TIEEVEN:
+    default:
+        rmode = float_round_nearest_even;
+        break;
+    case FPROUNDING_POSINF:
+        rmode = float_round_up;
+        break;
+    case FPROUNDING_NEGINF:
+        rmode = float_round_down;
+        break;
+    case FPROUNDING_ZERO:
+        rmode = float_round_to_zero;
+        break;
+    }
+    return rmode;
+}