1 files changed, 103 insertions, 0 deletions
diff --git a/neozip/arch/riscv/crc32_zbc.c b/neozip/arch/riscv/crc32_zbc.c
new file mode 100644
index 0000000000..cf52279b80
--- /dev/null
+++ b/neozip/arch/riscv/crc32_zbc.c
@@ -0,0 +1,103 @@
+/* crc32_zbc.c - RISCV Zbc version of crc32
+ * Copyright (C) 2025 ByteDance. All rights reserved.
+ * Contributed by Yin Tong <yintong.ustc@bytedance.com>
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#ifdef RISCV_CRC32_ZBC
+
+#include "zbuild.h"
+#include "arch_functions.h"
+
+#define CLMUL_MIN_LEN 16   // Minimum size of buffer for _crc32_clmul
+#define CLMUL_CHUNK_LEN 16 // Length of chunk for clmul
+
+#define CONSTANT_R3 0x1751997d0ULL
+#define CONSTANT_R4 0x0ccaa009eULL
+#define CONSTANT_R5 0x163cd6124ULL
+#define MASK32 0xFFFFFFFF
+#define CRCPOLY_TRUE_LE_FULL 0x1DB710641ULL
+#define CONSTANT_RU 0x1F7011641ULL
+
+static inline uint64_t clmul(uint64_t a, uint64_t b) {
+    uint64_t res;
+    __asm__ volatile("clmul %0, %1, %2" : "=r"(res) : "r"(a), "r"(b));
+    return res;
+}
+
+static inline uint64_t clmulh(uint64_t a, uint64_t b) {
+    uint64_t res;
+    __asm__ volatile("clmulh %0, %1, %2" : "=r"(res) : "r"(a), "r"(b));
+    return res;
+}
+
+Z_FORCEINLINE static uint32_t crc32_clmul_impl(uint64_t crc, const unsigned char *buf, uint64_t len) {
+    const uint64_t *buf64 = (const uint64_t *)buf;
+    uint64_t low = buf64[0] ^ crc;
+    uint64_t high = buf64[1];
+
+    if (len < 16)
+        goto finish_fold;
+    len -= 16;
+    buf64 += 2;
+
+    // process each 16-byte block
+    while (len >= 16) {
+        uint64_t t2 = clmul(CONSTANT_R4, high);
+        uint64_t t3 = clmulh(CONSTANT_R4, high);
+
+        uint64_t t0_new = clmul(CONSTANT_R3, low);
+        uint64_t t1_new = clmulh(CONSTANT_R3, low);
+
+        // Combine the results and XOR with new data
+        low = t0_new ^ t2;
+        high = t1_new ^ t3;
+        low ^= buf64[0];
+        high ^= buf64[1];
+
+        buf64 += 2;
+        len -= 16;
+    }
+
+finish_fold:
+    // Fold the 128-bit result into 64 bits
+    uint64_t fold_t3 = clmulh(low, CONSTANT_R4);
+    uint64_t fold_t2 = clmul(low, CONSTANT_R4);
+    low = high ^ fold_t2;
+    high = fold_t3;
+
+    // Combine the low and high parts and perform polynomial reduction
+    uint64_t combined = (low >> 32) | ((high & MASK32) << 32);
+    uint64_t reduced_low = clmul(low & MASK32, CONSTANT_R5) ^ combined;
+
+    // Barrett reduction step
+    uint64_t barrett = clmul(reduced_low & MASK32, CONSTANT_RU) & MASK32;
+    barrett = clmul(barrett, CRCPOLY_TRUE_LE_FULL);
+    uint64_t final = barrett ^ reduced_low;
+
+    // Return the high 32 bits as the final CRC
+    return (uint32_t)(final >> 32);
+}
+
+Z_INTERNAL uint32_t crc32_riscv64_zbc(uint32_t crc, const uint8_t *buf, size_t len) {
+    if (len < CLMUL_MIN_LEN) {
+        return crc32_braid(crc, buf, len);
+    }
+
+    uint64_t unaligned_length = len % CLMUL_CHUNK_LEN;
+    if (unaligned_length) {
+        crc = crc32_braid(crc, buf, unaligned_length);
+        buf += unaligned_length;
+        len -= unaligned_length;
+    }
+
+    crc = crc32_clmul_impl(~crc, buf, len);
+    return ~crc;
+}
+
+Z_INTERNAL uint32_t crc32_copy_riscv64_zbc(uint32_t crc, uint8_t *dst, const uint8_t *src, size_t len) {
+    crc = crc32_riscv64_zbc(crc, src, len);
+    memcpy(dst, src, len);
+    return crc;
+}
+#endif