intermediate changes

ref:cde9a383711a11544ce7e107a78147fb96cc4029

1 files changed, 56 insertions, 0 deletions

diff --git a/library/cpp/digest/old_crc/gencrc/main.cpp b/library/cpp/digest/old_crc/gencrc/main.cpp
new file mode 100644
index 0000000000..d5821304ce
--- /dev/null
+++ b/library/cpp/digest/old_crc/gencrc/main.cpp
@@ -0,0 +1,56 @@
+#include <util/stream/output.h>
+
+#define POLY_16 0x1021
+#define POLY_32 0xEDB88320UL
+#define POLY_64 ULL(0xE543279765927881)
+
+static void crc16init() {
+    ui32 CRCTAB16[256];
+    ui32 crc;
+    int i, j;
+
+    for (i = 0; i < 256; CRCTAB16[i++] = 0xFFFF & ((crc << 8) ^ (crc >> 8)))
+        for (crc = i, j = 8; j > 0; j--)
+            if (crc & 1)
+                crc = (crc >> 1) ^ POLY_16;
+            else
+                crc >>= 1;
+
+    for (size_t k = 0; k < 256; ++k) {
+        Cout << "    ULL(" << CRCTAB16[k] << ")";
+
+        if (k != 255) {
+            Cout << ",\n";
+        }
+    }
+}
+
+static void crc32init() {
+    ui32 CRCTAB32[256];
+    ui32 crc;
+    int i, j;
+
+    for (i = 0; i < 256; CRCTAB32[i++] = crc)
+        for (crc = i, j = 8; j > 0; j--)
+            if (crc & 1)
+                crc = (crc >> 1) ^ POLY_32;
+            else
+                crc >>= 1;
+
+    for (size_t k = 0; k < 256; ++k) {
+        Cout << "    ULL(" << CRCTAB32[k] << ")";
+
+        if (k != 255) {
+            Cout << ",\n";
+        }
+    }
+}
+
+int main() {
+    Cout << "static const ui32 CRCTAB16[] = {\n\n";
+    crc16init();
+    Cout << "\n};\n\n";
+    Cout << "static const ui32 CRCTAB32[] = {\n\n";
+    crc32init();
+    Cout << "\n};\n\n";
+}