初始提交

Project/Src/rt-thread/components/libc/compilers/minilibc/rand.c

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+/*
+ * Copyright (c) 2006-2018, RT-Thread Development Team
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ *
+ * Change Logs:
+ * Date           Author       Notes
+ */
+#include <stdlib.h>
+#include <stdint.h>
+#include <sys/types.h>
+
+static unsigned int _seed=1;
+
+/* Knuth's TAOCP section 3.6 */
+#define	M	((1U<<31) -1)
+#define	A	48271
+#define	Q	44488		// M/A
+#define	R	3399		// M%A; R < Q !!!
+
+int rand_r(unsigned int* seed)
+{   int32_t X;
+
+    X = *seed;
+    X = A*(X%Q) - R * (int32_t) (X/Q);
+    if (X < 0)
+	X += M;
+
+    *seed = X;
+    return X;
+}
+
+int rand(void) {
+  return rand_r(&_seed);
+}
+
+void srand(unsigned int i)
+{ 
+	_seed=i;
+}
+
+int random(void) __attribute__((alias("rand")));
+void srandom(unsigned int i) __attribute__((alias("srand")));