Initial project import

tools/v/vlib/hash/crc64/interop/README.md

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+# CRC64 Interoperability Fixture
+
+This directory contains interoperability tests for the V `hash.crc64` module, cross-validating
+against reference implementations in C and Python.
+
+## Overview
+
+The fixture verifies that `hash.crc64` produces identical CRC-64-ECMA-182 checksums when:
+- Computing the same data in V, C, and Python
+- Operating on various input patterns (empty, binary, text, large payloads)
+
+This helps catch:
+- Bit-ordering errors
+- Polynomial table generation bugs
+- Byte-order issues
+- Implementation divergences
+
+## Files
+
+- `crc64_interop.vsh` - Main V interop checker script
+- `crc64_ref.c` - C reference implementation (auto-compiled)
+- `crc64_ref.py` - Python reference implementation
+
+## Running the fixture
+
+From the V repository root:
+
+```bash
+v run vlib/hash/crc64/interop/crc64_interop.vsh
+```
+
+## Test vectors
+
+The fixture tests 10 vector categories:
+
+1. **empty** - Zero-length input
+2. **single_a** - Single character 'a'
+3. **single_null** - Single null byte
+4. **text_123456789** - Standard test vector
+5. **text_hello_world** - Common greeting
+6. **all_zeros_16** - 16 zero bytes
+7. **all_ones_16** - 16 0xFF bytes
+8. **repeating_pattern** - 150 bytes of "abc" repeated
+9. **all_bytes** - All 256 byte values in sequence
+10. **large_payload** - 10000 bytes of "test data " repeated
+
+Each vector is checksummed by:
+- V: `hash.crc64.sum(data)`
+- C: compiled from `crc64_ref.c`
+- Python: `crc64_ref.py`
+
+## Polynomial
+
+All implementations use CRC-64-ECMA-182:
+- Polynomial: `0x42F0E1EBA9EA3693`
+- Initial value: `0x0000000000000000`
+- Final XOR: `0x0000000000000000`
+- Check value for `"123456789"`: `0x6c40df5f0b497347`
+
+## Prerequisites
+
+- V compiler (tested with current repo version)
+- GCC (to compile C reference)
+- Python 3 (for Python reference)
+
+## Expected output
+
+```
+Compiling C reference helper...
+Running cross-validation tests...
+OK: empty => 0x0000000000000000
+OK: single_a => 0x926a79e87a919f5d
+OK: single_null => 0xbd4a6ec89c7eaafb
+...
+=== Results ===
+Passed: 10
+Failed: 0
+Total:  10
+```
+
+## Troubleshooting
+
+If the fixture fails:
+1. Ensure `gcc` and `python3` are in PATH
+2. Check that `hash.crc64` module can be imported (`v -silent test vlib/hash/crc64/`)
+3. Manual check: `python3 crc64_ref.py checksum 313233343536373839` (should match C)

tools/v/vlib/hash/crc64/interop/crc64_interop.vsh

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+#!/usr/bin/env -S ./vnew run
+
+import os
+import hash.crc64
+
+struct TestVector {
+	name string
+	data []u8
+}
+
+const ecma_check_123456789 = u64(0x6c40df5f0b497347)
+
+fn compile_c_helper(dir string) string {
+	ref_c := os.join_path(dir, 'crc64_ref.c')
+	ref_bin := os.join_path(dir, 'crc64_ref')
+
+	// Compile: gcc -std=c99 crc64_ref.c -o crc64_ref
+	cmd := 'gcc -std=c99 "${ref_c}" -o "${ref_bin}"'
+	result := os.execute(cmd)
+	if result.exit_code != 0 {
+		eprintln('Failed to compile C helper:')
+		eprintln(result.output)
+		exit(1)
+	}
+
+	return ref_bin
+}
+
+fn run_c_checksum(ref_bin string, data []u8) !u64 {
+	hex_str := data.hex()
+	cmd := '${ref_bin} checksum ${hex_str}'
+	result := os.execute(cmd)
+	if result.exit_code != 0 {
+		return error('C helper failed: ${result.output}')
+	}
+
+	result_str := result.output.trim_space()
+	return u64(result_str.parse_uint(16, 64)!)
+}
+
+fn run_python_checksum(dir string, data []u8) !u64 {
+	ref_py := os.join_path(dir, 'crc64_ref.py')
+	hex_str := data.hex()
+	cmd := 'python3 "${ref_py}" checksum ${hex_str}'
+	result := os.execute(cmd)
+	if result.exit_code != 0 {
+		return error('Python helper failed: ${result.output}')
+	}
+
+	result_str := result.output.trim_space()
+	return u64(result_str.parse_uint(16, 64)!)
+}
+
+fn test_vector(name string, data []u8, ref_bin string, dir string) ! {
+	// V checksum
+	v_sum := crc64.sum(data)
+
+	// C checksum
+	c_sum := run_c_checksum(ref_bin, data)!
+
+	// Python checksum
+	py_sum := run_python_checksum(dir, data)!
+
+	// All must match
+	if v_sum != c_sum || v_sum != py_sum {
+		eprintln('FAIL: ${name}')
+		eprintln('  V:      0x${v_sum:016x}')
+		eprintln('  C:      0x${c_sum:016x}')
+		eprintln('  Python: 0x${py_sum:016x}')
+		return error('checksum mismatch')
+	}
+
+	if name == 'text_123456789' && v_sum != ecma_check_123456789 {
+		eprintln('FAIL: ${name}')
+		eprintln('  V:        0x${v_sum:016x}')
+		eprintln('  Expected: 0x${ecma_check_123456789:016x}')
+		return error('unexpected CRC-64-ECMA-182 check value')
+	}
+
+	println('OK: ${name} => 0x${v_sum:016x}')
+}
+
+fn main() {
+	dir := os.dir(@FILE)
+
+	println('Compiling C reference helper...')
+	ref_bin := compile_c_helper(dir)
+	defer { os.rm(ref_bin) or {} }
+
+	println('Running cross-validation tests...')
+	mut passed := 0
+	mut failed := 0
+
+	mut vectors := []TestVector{}
+	vectors << TestVector{'empty', []u8{}}
+	vectors << TestVector{'single_a', 'a'.bytes()}
+	vectors << TestVector{'single_null', [u8(0)]}
+	vectors << TestVector{'text_123456789', '123456789'.bytes()}
+	vectors << TestVector{'text_hello_world', 'Hello, World!'.bytes()}
+	vectors << TestVector{'all_zeros_16', []u8{len: 16}}
+	vectors << TestVector{'all_ones_16', []u8{len: 16, init: 0xFF}}
+	vectors << TestVector{'repeating_pattern', ('abc'.repeat(50)).bytes()}
+
+	mut all_bytes := []u8{len: 256}
+	for i in 0 .. 256 {
+		all_bytes[i] = u8(i)
+	}
+	vectors << TestVector{'all_bytes', all_bytes}
+	vectors << TestVector{'large_payload', ('test data '.repeat(1000)).bytes()}
+
+	for vec in vectors {
+		test_vector(vec.name, vec.data, ref_bin, dir) or {
+			eprintln('  Error: ${err}')
+			failed++
+			continue
+		}
+		passed++
+	}
+
+	println('')
+	println('=== Results ===')
+	println('Passed: ${passed}')
+	println('Failed: ${failed}')
+	println('Total:  ${passed + failed}')
+
+	if failed > 0 {
+		exit(1)
+	}
+}

tools/v/vlib/hash/crc64/interop/crc64_ref.c

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+// Standard CRC64-ECMA reference implementation in C
+// Compiles with: gcc -std=c99 crc64_ref.c -o crc64_ref
+
+#include <stdio.h>
+#include <stdint.h>
+#include <string.h>
+#include <stdlib.h>
+
+#define CRC64_ECMA 0x42F0E1EBA9EA3693ULL
+
+static uint64_t crc64_table[256];
+
+void crc64_init_table(void) {
+	for (int i = 0; i < 256; i++) {
+		uint64_t crc = (uint64_t)i << 56;
+		for (int j = 0; j < 8; j++) {
+			if (crc & 0x8000000000000000ULL) {
+				crc = (crc << 1) ^ CRC64_ECMA;
+			} else {
+				crc <<= 1;
+			}
+		}
+		crc64_table[i] = crc;
+	}
+}
+
+uint64_t crc64_checksum(const uint8_t *data, size_t len) {
+	uint64_t crc = 0ULL;
+	for (size_t i = 0; i < len; i++) {
+		uint8_t byte = data[i];
+		crc = crc64_table[(uint8_t)((crc >> 56) ^ byte)] ^ (crc << 8);
+	}
+	return crc;
+}
+
+int main(int argc, char *argv[]) {
+	crc64_init_table();
+
+	if (argc < 2) {
+		fprintf(stderr, "Usage: %s <action> [data...]\n", argv[0]);
+		fprintf(stderr, "  checksum <hexstring>  - compute CRC64 of hex data\n");
+		fprintf(stderr, "  table                 - print first 16 table entries\n");
+		return 1;
+	}
+
+	const char *action = argv[1];
+
+	if (strcmp(action, "table") == 0) {
+		printf("CRC64_ECMA table (first 16):\n");
+		for (int i = 0; i < 16; i++) {
+			printf("  [%d] = 0x%016llx\n", i, (unsigned long long)crc64_table[i]);
+		}
+		return 0;
+	}
+
+	if (strcmp(action, "checksum") == 0) {
+		const char *hexstr = (argc > 2) ? argv[2] : "";
+		size_t hexlen = strlen(hexstr);
+
+		if (hexlen == 0) {
+			// Empty input
+			uint64_t crc = crc64_checksum(NULL, 0);
+			printf("%016llx\n", (unsigned long long)crc);
+			return 0;
+		}
+
+		if (hexlen % 2 != 0) {
+			fprintf(stderr, "Error: hex string must have even length\n");
+			return 1;
+		}
+
+		size_t datalen = hexlen / 2;
+		uint8_t *data = malloc(datalen);
+		if (!data) {
+			fprintf(stderr, "Error: memory allocation failed\n");
+			return 1;
+		}
+
+		for (size_t i = 0; i < datalen; i++) {
+			unsigned int byte;
+			if (sscanf(&hexstr[i * 2], "%2x", &byte) != 1) {
+				fprintf(stderr, "Error: invalid hex character\n");
+				free(data);
+				return 1;
+			}
+			data[i] = (uint8_t)byte;
+		}
+
+		uint64_t crc = crc64_checksum(data, datalen);
+		printf("%016llx\n", (unsigned long long)crc);
+		free(data);
+		return 0;
+	}
+
+	fprintf(stderr, "Error: unknown action '%s'\n", action);
+	return 1;
+}
+

tools/v/vlib/hash/crc64/interop/crc64_ref.py

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+#!/usr/bin/env python3
+"""CRC64-ECMA reference implementation in Python."""
+
+import sys
+import binascii
+
+CRC64_ECMA = 0x42F0E1EBA9EA3693
+
+class CRC64:
+    def __init__(self):
+        self.table = self._make_table(CRC64_ECMA)
+
+    @staticmethod
+    def _make_table(poly):
+        table = []
+        for i in range(256):
+            crc = i << 56
+            for _ in range(8):
+                if crc & 0x8000000000000000:
+                    crc = (crc << 1) ^ poly
+                else:
+                    crc <<= 1
+            table.append(crc & 0xFFFFFFFFFFFFFFFF)
+        return table
+
+    def checksum(self, data):
+        """Compute CRC64 checksum of data."""
+        crc = 0
+        for byte in data:
+            crc = self.table[((crc >> 56) ^ byte) & 0xFF] ^ ((crc << 8) & 0xFFFFFFFFFFFFFFFF)
+        return crc & 0xFFFFFFFFFFFFFFFF
+
+
+def main():
+    crc = CRC64()
+
+    if len(sys.argv) < 2:
+        print("Usage: crc64_ref.py <action> [data...]", file=sys.stderr)
+        print("  checksum <hexstring>  - compute CRC64 of hex data", file=sys.stderr)
+        print("  table                 - print first 16 table entries", file=sys.stderr)
+        sys.exit(1)
+
+    action = sys.argv[1]
+
+    if action == "table":
+        print("CRC64_ECMA table (first 16):")
+        for i in range(16):
+            print(f"  [{i:2d}] = 0x{crc.table[i]:016x}")
+        return 0
+
+    if action == "checksum":
+        hexstr = sys.argv[2] if len(sys.argv) > 2 else ""
+        try:
+            data = binascii.unhexlify(hexstr) if hexstr else b""
+            result = crc.checksum(data)
+            print(f"{result:016x}")
+            return 0
+        except (binascii.Error, ValueError) as e:
+            print(f"Error: invalid hex input: {e}", file=sys.stderr)
+            sys.exit(1)
+
+    print(f"Error: unknown action '{action}'", file=sys.stderr)
+    sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()
+