1 files changed, 75 insertions, 0 deletions
diff --git a/circuitpython/py/smallint.c b/circuitpython/py/smallint.c
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+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * SPDX-FileCopyrightText: Copyright (c) 2013, 2014 Damien P. George
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "py/smallint.h"
+
+bool mp_small_int_mul_overflow(mp_int_t x, mp_int_t y) {
+    // Check for multiply overflow; see CERT INT32-C
+    if (x > 0) { // x is positive
+        if (y > 0) { // x and y are positive
+            if (x > (MP_SMALL_INT_MAX / y)) {
+                return true;
+            }
+        } else { // x positive, y nonpositive
+            if (y < (MP_SMALL_INT_MIN / x)) {
+                return true;
+            }
+        } // x positive, y nonpositive
+    } else { // x is nonpositive
+        if (y > 0) { // x is nonpositive, y is positive
+            if (x < (MP_SMALL_INT_MIN / y)) {
+                return true;
+            }
+        } else { // x and y are nonpositive
+            if (x != 0 && y < (MP_SMALL_INT_MAX / x)) {
+                return true;
+            }
+        } // End if x and y are nonpositive
+    } // End if x is nonpositive
+    return false;
+}
+
+mp_int_t mp_small_int_modulo(mp_int_t dividend, mp_int_t divisor) {
+    // Python specs require that mod has same sign as second operand
+    dividend %= divisor;
+    if ((dividend < 0 && divisor > 0) || (dividend > 0 && divisor < 0)) {
+        dividend += divisor;
+    }
+    return dividend;
+}
+
+mp_int_t mp_small_int_floor_divide(mp_int_t num, mp_int_t denom) {
+    if (num >= 0) {
+        if (denom < 0) {
+            num += -denom - 1;
+        }
+    } else {
+        if (denom >= 0) {
+            num += -denom + 1;
+        }
+    }
+    return num / denom;
+}