SVNからのミラー

Makefile

@@ -0,0 +1,4 @@
+all:
+	cc -o rng main.c -static -lc
+
+.PHONY: all

main.c

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+#include <stdint.h>
+
+static uint32_t x = 123456789, y = 362436069, z = 521288629, w = 88675123;
+
+static uint32_t xorshift128(void) {
+  uint32_t t = x;
+  t ^= t << 11;
+  t ^= t >> 8;
+  x = y; y = z; z = w;
+  w ^= w >> 19;
+  w ^= t;
+  return w;
+}
+
+uint32_t prand(void) {
+  return xorshift128();
+}
+
+void psrand(uint32_t seed) {
+  if (seed == 0) seed = 1;
+
+  x = seed;
+  y = seed ^ 0xDEADBEEF;
+  z = seed ^ 0xCAFEBABE;
+  w = seed ^ 0xF00DCAFE;
+
+  for (int i = 0; i < 10; i++) xorshift128();
+}
+
+uint32_t genseed(void) {
+  uint32_t seed = 0;
+  seed ^= (uint32_t)(uintptr_t)&seed;
+
+  uint32_t uninit_var;
+  seed ^= uninit_var;
+
+  volatile uint32_t counter = 0;
+  for (int i = 0; i < 1000; i++) counter += i;
+
+  seed ^= counter;
+  seed ^= (uint32_t)__LINE__ ^ (uint32_t)(uintptr_t)__FILE__;
+
+  x = seed;
+  y = seed ^ 0xDEADBEEF;
+  z = seed ^ 0xCAFEBABE;
+  w = seed ^ 0xF00DCAFE;
+  seed = xorshift128();
+
+  if (seed == 0) seed = 1;
+  return seed;
+}
+
+void uint_to_string(uint32_t num, char *buf, int *len) {
+  char tmp[11];
+  int i = 0;
+  if (num == 0) {
+    buf[0] = '0';
+    buf[1] = '\0';
+    *len = 1;
+    return;
+  }
+
+  while (num > 0) {
+    tmp[i++] = (num % 10) + '0';
+    num /= 10;
+  }
+
+  *len = i;
+  for (int j = 0; j < i; j++) buf[j] = tmp[i - 1 - j];
+
+  buf[i] = '\0';
+}
+
+static inline long syscall(long arg1, long arg2, long arg3) {
+#if defined(__linux__)
+  long num = 1;
+  long ret;
+  register long rdi asm("rdi") = arg1; // ファイルディスクリプタ
+  register long rsi asm("rsi") = arg2; // バッファー
+  register long rdx asm("rdx") = arg3; // 長さ
+  register long rax asm("rax") = num; // システムコール：書き込み
+  __asm__ volatile ("syscall"
+    : "=a"(ret)
+    : "r"(num), "r"(arg1), "r"(arg2), "r"(arg3)
+    : "rdi", "rsi", "rdx", "rcx", "r11", "memory");
+
+  return ret;
+#elif defined(__FreeBSD__)
+  long num = 4;
+  long ret;
+  __asm__ volatile (
+    "mov %1, %%rax\n"
+    "mov %2, %%rdi\n"
+    "mov %3, %%rsi\n"
+    "mov %4, %%rdx\n"
+    "syscall\n"
+    : "=a"(ret)
+    : "r"(num), "r"(arg1), "r"(arg2), "r"(arg3)
+    : "rdi", "rsi", "rdx", "rcx", "r8", "r9", "r10", "r11", "memory", "cc"
+  );
+  return ret;
+#else
+  return 0;
+#endif
+}
+
+int main(void) {
+  psrand(genseed());
+
+  char buf[32];
+  int blen;
+  int min = 0x01, max = 0xFF;
+  int random = min + (prand() % (max - min + 1));
+
+  uint_to_string(random, buf, &blen);
+  syscall(1, (long)buf, blen);
+  syscall(1, (long)"\n", 1);
+
+  return 0;
+}