From 85b042bec91960f4b38d7675ee6b8108e9df9b84 Mon Sep 17 00:00:00 2001
From: Philippe PITTOLI <karchnu@karchnu.fr>
Date: Sun, 16 Jun 2024 01:17:46 +0200
Subject: [PATCH] Add hexdump.zig.

---
 src/hexdump.zig | 130 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 130 insertions(+)
 create mode 100644 src/hexdump.zig

diff --git a/src/hexdump.zig b/src/hexdump.zig
new file mode 100644
index 0000000..8f21436
--- /dev/null
+++ b/src/hexdump.zig
@@ -0,0 +1,130 @@
+const std = @import("std");
+
+pub fn hexdump(stream: anytype, header: []const u8, buffer: []const u8) std.posix.WriteError!void {
+    // Print a header.
+    if (header.len > 0) {
+        var hdr: [64]u8 = undefined;
+        const offset: usize = (hdr.len / 2) - ((header.len / 2) - 1);
+
+        @memset(hdr[0..hdr.len], ' ');
+        std.mem.copyForwards(u8, hdr[offset..hdr.len], header);
+
+        try stream.writeAll(hdr[0..hdr.len]);
+        try stream.writeAll("\n");
+    }
+
+    var hexb: u32 = 0;
+    var ascii: [16]u8 = undefined;
+    // First line, first left side (simple number).
+    try stream.print("\n  {d:0>4}:  ", .{hexb});
+
+    // Loop on all values in the buffer (i from 0 to buffer.len).
+    var i: u32 = 0;
+    while (i < buffer.len) : (i += 1) {
+        // Print actual hexadecimal value.
+        try stream.print("{X:0>2} ", .{buffer[i]});
+
+        // What to print (simple ascii text, right side).
+        if (buffer[i] >= ' ' and buffer[i] <= '~') {
+            ascii[(i % 16)] = buffer[i];
+        } else {
+            ascii[(i % 16)] = '.';
+        }
+
+        // Next input is a multiple of 8 = extra space.
+        if ((i + 1) % 8 == 0) {
+            try stream.writeAll(" ");
+        }
+
+        // No next input: print the right amount of spaces.
+        if ((i + 1) == buffer.len) {
+            // Each line is 16 bytes to print, each byte takes 3 characters.
+            var missing_spaces = 3 * (15 - (i % 16));
+            // Missing an extra space if the current index % 16 is less than 7.
+            if ((i % 16) < 7) {
+                missing_spaces += 1;
+            }
+            while (missing_spaces > 0) : (missing_spaces -= 1) {
+                try stream.writeAll(" ");
+            }
+        }
+
+        // Every 16 bytes: print ascii text and line return.
+
+        // Case 1: it's been 16 bytes AND it's the last byte to print.
+        if ((i + 1) % 16 == 0 and (i + 1) == buffer.len) {
+            try stream.print("{s}\n", .{ascii[0..ascii.len]});
+        }
+        // Case 2: it's been 16 bytes but it's not the end of the buffer.
+        else if ((i + 1) % 16 == 0 and (i + 1) != buffer.len) {
+            try stream.print("{s}\n", .{ascii[0..ascii.len]});
+            hexb += 16;
+            try stream.print("  {d:0>4}:  ", .{hexb});
+        }
+        // Case 3: not the end of the 16 bytes row but it's the end of the buffer.
+        else if ((i + 1) % 16 != 0 and (i + 1) == buffer.len) {
+            try stream.print(" {s}\n", .{ascii[0..((i + 1) % 16)]});
+        }
+        // Case 4: not the end of the 16 bytes row and not the end of the buffer.
+        //         Do nothing.
+    }
+
+    try stream.writeAll("\n");
+}
+
+const print = std.debug.print;
+
+test "36-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    const buffer = "hello this is a simple text to print";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+}
+
+test "32-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    const buffer = "THIS IS THE END, MY ONLY...  END";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+}
+
+test "26-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    const buffer = "hello this is another text";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+}
+
+test "1-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    const buffer = "h";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+}
+
+test "0-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    const buffer = "";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    const hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+}