From ab69e5e2a7694c5847a235f968e0bc0d65e655ec Mon Sep 17 00:00:00 2001
From: Avril <flanchan@cumallover.me>
Date: Sun, 15 Nov 2020 22:05:28 +0000
Subject: [PATCH] u64_to_hex

---
 include/hex.hpp | 35 +++++++++++++++++++++++++++++++++++
 src/hex.cpp     | 34 ++++++++++++++++++++++++++++++++--
 2 files changed, 67 insertions(+), 2 deletions(-)

diff --git a/include/hex.hpp b/include/hex.hpp
index 50a2c2f..aacfa97 100644
--- a/include/hex.hpp
+++ b/include/hex.hpp
@@ -5,4 +5,39 @@
 namespace hv {
   /// Print a single screen
   void print_screen(const span<unsigned char> bytes, unsigned long offset);
+
+  inline void lookup_hex_string(std::uint64_t x, char* s)
+  {
+    static const char digits[513] =
+      "000102030405060708090a0b0c0d0e0f"
+      "101112131415161718191a1b1c1d1e1f"
+      "202122232425262728292a2b2c2d2e2f"
+      "303132333435363738393a3b3c3d3e3f"
+      "404142434445464748494a4b4c4d4e4f"
+      "505152535455565758595a5b5c5d5e5f"
+      "606162636465666768696a6b6c6d6e6f"
+      "707172737475767778797a7b7c7d7e7f"
+      "808182838485868788898a8b8c8d8e8f"
+      "909192939495969798999a9b9c9d9e9f"
+      "a0a1a2a3a4a5a6a7a8a9aaabacadaeaf"
+      "b0b1b2b3b4b5b6b7b8b9babbbcbdbebf"
+      "c0c1c2c3c4c5c6c7c8c9cacbcccdcecf"
+      "d0d1d2d3d4d5d6d7d8d9dadbdcdddedf"
+      "e0e1e2e3e4e5e6e7e8e9eaebecedeeef"
+      "f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff";
+    int i = 7;
+    const char *lut = (const char *)digits;
+    while (i >= 0)
+      {
+	int pos = (x & 0xFF) * 2;
+	char ch = lut[pos];
+	s[i * 2] = ch;
+
+	ch = lut[pos + 1];
+	s[i * 2 + 1] = ch;
+
+	x >>= 8;
+	i -= 1;
+      }
+  }
 }
diff --git a/src/hex.cpp b/src/hex.cpp
index 4e099bc..b314264 100644
--- a/src/hex.cpp
+++ b/src/hex.cpp
@@ -1,5 +1,6 @@
 #include <fmt/format.h>
 #include <span.hpp>
+#include <hex.hpp>
 
 const static constexpr char ascii_map[256] = {
   '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', '.', 
@@ -71,6 +72,22 @@ inline __attribute__((always_inline)) void print_exact(const char (&ar)[N])
 	fwrite(ar, N, 1, stdout);
 }
 
+inline static void u64_to_hex(std::uint64_t num, char* s)
+{
+	hv::lookup_hex_string(num, s);
+#if 0
+	std::uint64_t x = num;
+	x = ((x & 0xFFFF) << 32) | ((x & 0xFFFF0000) >> 16);
+	x = ((x & 0x0000FF000000FF00) >> 8) | (x & 0x000000FF000000FF) << 16;
+	x = ((x & 0x00F000F000F000F0) >> 4) | (x & 0x000F000F000F000F) << 8;
+
+	uint64_t mask = ((x + 0x0606060606060606) >> 4) & 0x0101010101010101;
+	x += 0x27 * mask;
+
+	*(uint64_t *)s = x;
+#endif
+}
+
 namespace hv {
 	void print_screen(const span<unsigned char> memory, unsigned long offset)
 	{
@@ -82,7 +99,17 @@ namespace hv {
 #define S
 #define P_EX(n, buf) print_exact(buf)
 #endif
-		fmt::print("0x{:016x}  ", offset);
+		char posbuf[3 + 16 + 2] = { '0' };
+		posbuf[0] = '\n';
+		posbuf[1] = '0';
+		posbuf[2] = 'x';
+
+		posbuf[3 + 16] = ' ';
+		posbuf[3 + 16 + 1] = ' ';
+
+		u64_to_hex(offset, posbuf+3);
+		prints(posbuf+1);
+
 		char hxbuf[3];
 		std::size_t i=0;
 		char r_ascii[2 + ROW_SZ];
@@ -94,11 +121,14 @@ namespace hv {
 		for(;i<memory.size();i++) {
 			if (i && i % ROW_SZ == 0) { //TODO: Change to i +=16 so we don't have to branch here on every byte. Make sure to not overrun buffer tho
 				P_EX(S, r_ascii);
-				fmt::print("\n0x{:016x}  ", i+offset); //TODO: Implement this manually then write the buffer with `print_exact`
+
+				u64_to_hex(i+offset, posbuf+3);
+				print_exact(posbuf);
 			}
 			unsigned char idx = memory[i];
 			hex02(idx, hxbuf);
 			print_exact(hxbuf);
+
 			ascii[i%ROW_SZ] = ascii_map[idx];
 		}
 		if (memory.size() % ROW_SZ != 0)