1 files changed, 88 insertions, 0 deletions
diff --git a/neozip/arch/generic/compare256_c.c b/neozip/arch/generic/compare256_c.c
new file mode 100644
index 0000000000..6934a55565
--- /dev/null
+++ b/neozip/arch/generic/compare256_c.c
@@ -0,0 +1,88 @@
+/* compare256.c -- 256 byte memory comparison with match length return
+ * Copyright (C) 2020 Nathan Moinvaziri
+ * For conditions of distribution and use, see copyright notice in zlib.h
+ */
+
+#include "zbuild.h"
+#include "zendian.h"
+#include "deflate.h"
+#include "fallback_builtins.h"
+
+/* 8-bit integer comparison for hardware without unaligned loads */
+static inline uint32_t compare256_8_static(const uint8_t *src0, const uint8_t *src1) {
+    uint32_t len = 0;
+
+    do {
+        if (src0[0] != src1[0])
+            return len;
+        if (src0[1] != src1[1])
+            return len + 1;
+        if (src0[2] != src1[2])
+            return len + 2;
+        if (src0[3] != src1[3])
+            return len + 3;
+        if (src0[4] != src1[4])
+            return len + 4;
+        if (src0[5] != src1[5])
+            return len + 5;
+        if (src0[6] != src1[6])
+            return len + 6;
+        if (src0[7] != src1[7])
+            return len + 7;
+        src0 += 8, src1 += 8, len += 8;
+    } while (len < 256);
+
+    return 256;
+}
+
+/* 64-bit integer comparison for hardware with unaligned loads */
+static inline uint32_t compare256_64_static(const uint8_t *src0, const uint8_t *src1) {
+    uint32_t len = 0;
+
+    do {
+        uint64_t sv = zng_memread_8(src0);
+        uint64_t mv = zng_memread_8(src1);
+        uint64_t diff = sv ^ mv;
+        if (diff)
+            return len + zng_ctz64(Z_U64_TO_LE(diff)) / 8;
+        src0 += 8, src1 += 8, len += 8;
+
+        sv = zng_memread_8(src0);
+        mv = zng_memread_8(src1);
+        diff = sv ^ mv;
+        if (diff)
+            return len + zng_ctz64(Z_U64_TO_LE(diff)) / 8;
+        src0 += 8, src1 += 8, len += 8;
+    } while (len < 256);
+
+    return 256;
+}
+
+#if OPTIMAL_CMP == 8
+#  define COMPARE256 compare256_8_static
+#else
+#  define COMPARE256 compare256_64_static
+#endif
+
+#ifdef WITH_ALL_FALLBACKS
+Z_INTERNAL uint32_t compare256_8(const uint8_t *src0, const uint8_t *src1) {
+    return compare256_8_static(src0, src1);
+}
+
+Z_INTERNAL uint32_t compare256_64(const uint8_t *src0, const uint8_t *src1) {
+    return compare256_64_static(src0, src1);
+}
+#endif
+
+Z_INTERNAL uint32_t compare256_c(const uint8_t *src0, const uint8_t *src1) {
+    return COMPARE256(src0, src1);
+}
+
+// Generate longest_match_c
+#define LONGEST_MATCH       longest_match_c
+#include "match_tpl.h"
+
+// Generate longest_match_slow_c
+#define LONGEST_MATCH_SLOW
+#define LONGEST_MATCH       longest_match_slow_c
+#include "match_tpl.h"