py/modbuiltins: Implement abs() by dispatching to MP_UNARY_OP_ABS.

This allows user classes to implement __abs__ special method, and saves
code size (104 bytes for x86_64), even though during refactor, an issue
was fixed and few optimizations were made:

* abs() of minimum (negative) small int value is calculated properly.
* objint_longlong and objint_mpz avoid allocating new object is the
  argument is already non-negative.

1 files changed, 9 insertions, 0 deletions

diff --git a/py/objfloat.c b/py/objfloat.c
index fadbbcb79..fefd78314 100644
--- a/py/objfloat.c
+++ b/py/objfloat.c
@@ -162,6 +162,15 @@ STATIC mp_obj_t float_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
         case MP_UNARY_OP_HASH: return MP_OBJ_NEW_SMALL_INT(mp_float_hash(val));
         case MP_UNARY_OP_POSITIVE: return o_in;
         case MP_UNARY_OP_NEGATIVE: return mp_obj_new_float(-val);
+        case MP_UNARY_OP_ABS: {
+            mp_float_t value = mp_obj_float_get(o_in);
+            // TODO check for NaN etc
+            if (value < 0) {
+                return mp_obj_new_float(-value);
+            } else {
+                return o_in;
+            }
+        }
         default: return MP_OBJ_NULL; // op not supported
     }
 }