Unify CRC Implementation - Replace with crc-fast

Problem Description

The project currently uses multiple different CRC calculation libraries:

• crc-fast = "1.6.0"
• crc32c = "0.6.8"
• crc32fast = "1.5.0"
• crc64fast-nvme = "1.2.1"

This multi-library approach causes:

1. Code redundancy - Multiple implementations of the same functionality
2. Maintenance complexity - Need to familiarize with multiple library APIs
3. Performance inconsistency - Different libraries may have performance variations
4. Dependency bloat - Increases final binary size

Goal

Migrate all CRC calculations to use the crc-fast library exclusively and remove dependencies on other CRC libraries.

Migration Requirements

1. Dependency Management

# Remove
crc32c = "0.6.8"
crc32fast = "1.5.0"
crc64fast-nvme = "1.2.1"

# Keep and potentially upgrade
crc-fast = "1.6.0"  # or consider upgrading to latest version

2. API Migration Guide

From crc32c

// Original code
use crc32c::crc32c;
let checksum = crc32c(&data);

// New code
use crc_fast::Crc;
let crc = Crc::<u32>::new(&crc_fast::CRC_32_ISCSI); // CRC-32C (ISCSI)
let checksum = crc.calculate(&data);

From crc32fast

// Original code
use crc32fast::Hasher;
let mut hasher = Hasher::new();
hasher.update(&data);
let checksum = hasher.finalize();

// New code
use crc_fast::Crc;
let crc = Crc::<u32>::new(&crc_fast::CRC_32_ISO_HDLC);
let checksum = crc.calculate(&data);

From crc64fast-nvme

// Original code
use crc64fast_nvme::Crc64;
let checksum = Crc64::new().checksum(&data);

// New code
use crc_fast::Crc;
let crc = Crc::<u64>::new(&crc_fast::CRC_64_ECMA_182);
let checksum = crc.calculate(&data);

Implementation Steps

Step 1: Analyze Existing Code Usage

• Use grep to analyze all CRC library usage locations
• Document CRC algorithm types for each usage scenario
• Confirm migration feasibility

Step 2: Create Unified CRC Adapter Layer

• Create unified interface in src/crc/mod.rs
• Implement all required CRC algorithm variants
• Maintain compatibility with original APIs

Step 3: Gradually Replace Calling Code

• First replace crc32c usage
• Then replace crc32fast usage
• Finally replace crc64fast-nvme usage
• Run tests to verify after each replacement

Step 4: Clean Up Dependencies and Code

• Remove unnecessary dependencies from Cargo.toml
• Remove adapter layer (if no longer needed)
• Run full test suite

Step 5: Performance Verification and Optimization

• Compare performance before and after migration
• Enable crc-fast SIMD features
• Conduct stress testing

Acceptance Criteria

• All CRC calculation functions work correctly
• Performance is not worse than original implementation
• All test cases pass
• Code review approved
• Dependency cleanup completed

Risk Control

1. Rollback plan: Keep git history of original code for easy rollback if needed
2. Phased implementation: Replace gradually to avoid large-scale changes at once
3. Performance testing: Compare performance before and after migration
4. Compatibility verification: Ensure CRC results match in all usage scenarios