From f99521c835fc384b081a6e329143d6a86eafe601 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=CE=A3=CF=84=CE=AD=CF=86=CE=B1=CE=BD=CE=BF=CF=82=20=22Coor?=
 =?UTF-8?q?nio/8924th=22=20=CE=92=CE=BB=CE=B1=CF=83=CF=84=CF=8C=CF=82?=
 <8924th@gmail.com>
Date: Tue, 27 Aug 2024 02:33:11 +0300
Subject: [PATCH] SHA1 class can now compute hash from char span too

---
 src/Assistants/SHA1.cpp | 25 +++++++++++++++++++++++++
 src/Assistants/SHA1.hpp |  4 ++++
 2 files changed, 29 insertions(+)

diff --git a/src/Assistants/SHA1.cpp b/src/Assistants/SHA1.cpp
index 697a437..b55e6ab 100644
--- a/src/Assistants/SHA1.cpp
+++ b/src/Assistants/SHA1.cpp
@@ -210,6 +210,25 @@ void SHA1::update(std::istream& is) {
 	}
 }
 
+void SHA1::update(std::span<const char> data) {
+	std::size_t offset{};
+
+	while (offset < data.size()) {
+		const auto chunksize{ std::min(BLOCK_BYTES - buffer.size(), data.size() - offset) };
+
+		buffer.append(data.data() + offset, chunksize);
+		offset += chunksize;
+
+		// If buffer is full, process the block
+		if (buffer.size() == BLOCK_BYTES) {
+			std::uint32_t block[BLOCK_INTS]{};
+			buffer_to_block(buffer, block);
+			transform(digest, block, transforms);
+			buffer.clear();
+		}
+	}
+}
+
 std::string SHA1::final() {
 	// total number of hashed bits
 	const std::uint64_t total_bits{ (transforms * BLOCK_BYTES + buffer.size()) * 8 };
@@ -253,3 +272,9 @@ std::string SHA1::from_file(const std::filesystem::path& filePath) {
 	checksum.update(stream);
 	return checksum.final();
 }
+
+std::string SHA1::from_span(const std::span<const char> fileData) {
+	SHA1 checksum;
+	checksum.update(fileData);
+	return checksum.final();
+}
diff --git a/src/Assistants/SHA1.hpp b/src/Assistants/SHA1.hpp
index 343f8ed..b7182ef 100644
--- a/src/Assistants/SHA1.hpp
+++ b/src/Assistants/SHA1.hpp
@@ -9,8 +9,10 @@
 
 #pragma once
 
+#include <span>
 #include <string>
 #include <cstdint>
+#include <sstream>
 #include <filesystem>
 
 class SHA1 {
@@ -22,7 +24,9 @@ class SHA1 {
 	SHA1();
 	void update(const std::string& s);
 	void update(std::istream& is);
+	void update(std::span<const char> data);
 	std::string final();
 
 	static std::string from_file(const std::filesystem::path& filePath);
+	static std::string from_span(const std::span<const char> fileData);
 };