From 8add41a6e37994577d928bc312801ddfa1c33173 Mon Sep 17 00:00:00 2001
From: lucy96chen <47800040+lucy96chen@users.noreply.github.com>
Date: Mon, 17 Oct 2022 17:38:59 -0700
Subject: Shader cache index implementation (#2452)

---
 source/core/slang-digest-util.cpp | 66 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 source/core/slang-digest-util.cpp

(limited to 'source/core/slang-digest-util.cpp')

diff --git a/source/core/slang-digest-util.cpp b/source/core/slang-digest-util.cpp
new file mode 100644
index 000000000..d235f2cf0
--- /dev/null
+++ b/source/core/slang-digest-util.cpp
@@ -0,0 +1,66 @@
+// string-digest-util.cpp
+#include "slang-digest-util.h"
+
+#include "../core/slang-basic.h"
+#include "../core/slang-digest-builder.h"
+#include "../core/slang-md5.h"
+#include "../core/slang-char-util.h"
+
+namespace Slang
+{
+
+/*static*/ Digest DigestUtil::computeDigestForStringSlice(UnownedStringSlice text)
+{
+    DigestBuilder builder;
+    builder.addToDigest(text);
+    return builder.finalize();
+}
+
+/*static*/ Digest DigestUtil::combine(const Digest& digestA, const Digest& digestB)
+{
+    DigestBuilder builder;
+    builder.addToDigest(digestA);
+    builder.addToDigest(digestB);
+    return builder.finalize();
+}
+
+/*static*/ String DigestUtil::toString(const Digest& digest)
+{
+    StringBuilder hashString;
+
+    uint8_t* uint8Hash = (uint8_t*)digest.values;
+
+    for (Index i = 0; i < 16; ++i)
+    {
+        auto hashSegmentString = String(uint8Hash[i], 16);
+
+        if (hashSegmentString.getLength() == 1)
+        {
+            hashString.append("0");
+        }
+        hashString.append(hashSegmentString.getBuffer());
+    }
+
+    return hashString;
+}
+
+/*static*/ Digest DigestUtil::fromString(UnownedStringSlice hashString)
+{
+    uint8_t uint8Hash[16];
+
+    // When the hash is converted to a String, ReverseInternalAscii is called
+    // at the very end. Since there is no way to get a char* for hashString to pass
+    // to ReverseInternalAscii to flip the string back, we instead loop starting from
+    // the end and work backwards towards the beginning.
+    for (Index i = 0; i < 16; i++)
+    {
+        uint8Hash[i] = (uint8_t)CharUtil::getHexDigitValue(hashString[i * 2]) * 16
+            + (uint8_t)CharUtil::getHexDigitValue(hashString[i * 2 + 1]);
+    }
+
+    Digest digest;
+    memcpy(digest.values, uint8Hash, 16);
+    return digest;
+}
+
+}
-- 
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