From cdb83b18ece63b13d6796e315f0737f833c1ee16 Mon Sep 17 00:00:00 2001
From: Jeff Epler <jepler@unpythonic.net>
Date: Thu, 22 Mar 2018 21:52:25 -0500
Subject: [PATCH] Implement * and *= for array.array

---
 py/objarray.c             | 33 +++++++++++++++++++++++++++++++++
 tests/basics/array_mul.py | 28 ++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+)
 create mode 100644 tests/basics/array_mul.py

diff --git a/py/objarray.c b/py/objarray.c
index a1a979b56f..eb053bd8a9 100644
--- a/py/objarray.c
+++ b/py/objarray.c
@@ -241,6 +241,39 @@ STATIC mp_obj_t array_unary_op(mp_unary_op_t op, mp_obj_t o_in) {
 STATIC mp_obj_t array_binary_op(mp_binary_op_t op, mp_obj_t lhs_in, mp_obj_t rhs_in) {
     mp_obj_array_t *lhs = MP_OBJ_TO_PTR(lhs_in);
     switch (op) {
+        case MP_BINARY_OP_MULTIPLY:
+        case MP_BINARY_OP_INPLACE_MULTIPLY: {
+            if (!MP_OBJ_IS_INT(rhs_in)) {
+                return MP_OBJ_NULL; // op not supported
+            }
+            mp_uint_t repeat = mp_obj_get_int(rhs_in);
+            bool inplace = (op == MP_BINARY_OP_INPLACE_MULTIPLY);
+            mp_buffer_info_t lhs_bufinfo;
+            array_get_buffer(lhs_in, &lhs_bufinfo, MP_BUFFER_READ);
+            mp_obj_array_t *res;
+            byte *ptr;
+            size_t orig_lhs_bufinfo_len = lhs_bufinfo.len;
+            if(inplace) {
+                res = lhs;
+                size_t item_sz = mp_binary_get_size('@', lhs->typecode, NULL);
+                lhs->items = m_renew(byte, lhs->items, (lhs->len + lhs->free) * item_sz, lhs->len * repeat * item_sz);
+                lhs->len = lhs->len * repeat;
+                lhs->free = 0;
+                if (!repeat)
+                    return MP_OBJ_FROM_PTR(res);
+                repeat--;
+                ptr = (byte*)res->items + orig_lhs_bufinfo_len;
+            } else {
+                res = array_new(lhs_bufinfo.typecode, lhs->len * repeat);
+                ptr = (byte*)res->items;
+            }
+            if(orig_lhs_bufinfo_len) {
+                for(;repeat--; ptr += orig_lhs_bufinfo_len) {
+                    memcpy(ptr, lhs_bufinfo.buf, orig_lhs_bufinfo_len);
+                }
+            }
+            return MP_OBJ_FROM_PTR(res);
+        }
         case MP_BINARY_OP_ADD: {
             // allow to add anything that has the buffer protocol (extension to CPython)
             mp_buffer_info_t lhs_bufinfo;
diff --git a/tests/basics/array_mul.py b/tests/basics/array_mul.py
new file mode 100644
index 0000000000..bb5f3aa6b1
--- /dev/null
+++ b/tests/basics/array_mul.py
@@ -0,0 +1,28 @@
+try:
+    import array
+except ImportError:
+    print("SKIP")
+    raise SystemExit
+
+a1 = array.array('I', [1])
+a2 = array.array('I', [2]) * 2
+a3 = (a1 + a2)
+print(a3)
+
+a3 *= 5
+print(a3)
+
+a3 *= 0
+print(a3)
+
+a4 = a2 * 0
+print(a4)
+
+a4 *= 0
+print(a4)
+
+a4 = a4 * 2
+print(a4)
+
+a4 *= 2
+print(a4)