From da501b9294f5b338ba74fc6d196108c084891b74 Mon Sep 17 00:00:00 2001
From: Stenzek <stenzek@gmail.com>
Date: Fri, 29 Nov 2024 15:04:25 +1000
Subject: [PATCH] StringUtil: Add ParseFixedHexString()

---
 src/common/string_util.h | 21 +++++++++++++++++++++
 src/core/bios.cpp        | 16 +---------------
 2 files changed, 22 insertions(+), 15 deletions(-)

diff --git a/src/common/string_util.h b/src/common/string_util.h
index cd259f504..e5b821840 100644
--- a/src/common/string_util.h
+++ b/src/common/string_util.h
@@ -260,6 +260,27 @@ ALWAYS_INLINE static bool IsHexDigit(T ch)
           (ch >= static_cast<T>('0') && ch <= static_cast<T>('9')));
 }
 
+/// Returns a byte array from the provided hex string, computed at compile-time.
+template<size_t Length>
+static constexpr std::array<u8, Length> ParseFixedHexString(const char str[])
+{
+  std::array<u8, Length> h{};
+  for (int i = 0; str[i] != '\0'; i++)
+  {
+    u8 nibble = 0;
+    char ch = str[i];
+    if (ch >= '0' && ch <= '9')
+      nibble = str[i] - '0';
+    else if (ch >= 'a' && ch <= 'z')
+      nibble = 0xA + (str[i] - 'a');
+    else if (ch >= 'A' && ch <= 'Z')
+      nibble = 0xA + (str[i] - 'A');
+
+    h[i / 2] |= nibble << (((i & 1) ^ 1) * 4);
+  }
+  return h;
+}
+
 /// StartsWith/EndsWith variants which aren't case sensitive.
 ALWAYS_INLINE static bool StartsWithNoCase(const std::string_view str, const std::string_view prefix)
 {
diff --git a/src/core/bios.cpp b/src/core/bios.cpp
index 767b5f53d..c8b0c7eab 100644
--- a/src/core/bios.cpp
+++ b/src/core/bios.cpp
@@ -21,21 +21,7 @@ namespace BIOS {
 
 static constexpr ImageInfo::Hash MakeHashFromString(const char str[])
 {
-  ImageInfo::Hash h{};
-  for (int i = 0; str[i] != '\0'; i++)
-  {
-    u8 nibble = 0;
-    char ch = str[i];
-    if (ch >= '0' && ch <= '9')
-      nibble = str[i] - '0';
-    else if (ch >= 'a' && ch <= 'z')
-      nibble = 0xA + (str[i] - 'a');
-    else if (ch >= 'A' && ch <= 'Z')
-      nibble = 0xA + (str[i] - 'A');
-
-    h[i / 2] |= nibble << (((i & 1) ^ 1) * 4);
-  }
-  return h;
+  return StringUtil::ParseFixedHexString<ImageInfo::HASH_SIZE>(str);
 }
 
 // clang-format off