1 files changed, 71 insertions, 0 deletions
diff --git a/libs/libc/random.c b/libs/libc/random.c
new file mode 100644
index 0000000..2801029
--- /dev/null
+++ b/libs/libc/random.c
@@ -0,0 +1,71 @@
+// MIT License, Copyright (c) 2020 Marvin Borner
+
+#include <cpu.h>
+#include <def.h>
+#include <mem.h>
+#include <random.h>
+
+static u32 g_seed = 1;
+
+void srand(u32 seed)
+{
+	g_seed = seed;
+}
+
+u32 rdrand(void)
+{
+#ifdef kernel
+	if (!cpu_has_cfeature(CPUID_FEAT_ECX_RDRND))
+		return rand();
+
+	u32 rd;
+	__asm__ volatile("1:\n"
+			 "rdrand %0\n"
+			 "jnc 1b\n"
+			 : "=r"(rd));
+	return rd;
+#else
+	return rand();
+#endif
+}
+
+u32 rdseed(void)
+{
+#ifdef kernel
+	if (!cpu_has_cfeature(CPUID_FEAT_ECX_RDRND))
+		return rand();
+
+	u32 rd;
+	__asm__ volatile("1:\n"
+			 "rdseed %0\n"
+			 "jnc 1b\n"
+			 : "=r"(rd));
+	return rd;
+#else
+	return rand();
+#endif
+}
+
+u32 rand(void)
+{
+	g_seed = g_seed * 1103515245 + 12345;
+	return (g_seed >> 16) & 0x7FFF;
+}
+
+char *randstr(u32 size)
+{
+	if (!size)
+		return NULL;
+
+	char *buf = malloc(size + 1);
+	const char charset[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789";
+
+	size--;
+	for (u32 i = 0; i < size; i++) {
+		int key = rand() % (sizeof(charset) - 1);
+		buf[i] = charset[key];
+	}
+	buf[size] = '\0';
+
+	return buf;
+}