Hexdump: complete rewrite, fixes all known problems.

zig-impl/src/hexdump.zig

@@ -2,8 +2,7 @@ const std = @import("std");
 const print = std.debug.print;
 
 pub fn hexdump(stream: anytype, header: [] const u8, buffer: [] const u8) std.os.WriteError!void {
-    try stream.writeAll("\n");
-
+    // Print a header.
     if (header.len > 0) {
         var hdr: [64] u8 = undefined;
         var offset: usize = (hdr.len / 2) - ((header.len / 2) - 1);
@@ -17,52 +16,117 @@ pub fn hexdump(stream: anytype, header: [] const u8, buffer: [] const u8) std.os
 
     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)] = '.';
         }
 
-        if ((i + 1) % 8 == 0 or (i + 1) == buffer.len) {
+        // Next input is a multiple of 8 = extra space.
+        if ((i + 1) % 8 == 0) {
             try stream.writeAll(" ");
+        }
 
-            if ((i + 1) % 16 == 0) {
-                hexb += 16;
-
-                if ((i + 1) != buffer.len) {
-                    try stream.print("{s}\n  {d:0>4}:  ", .{ ascii[0..ascii.len], hexb });
-                } else {
-                    try stream.print("{s}\n", .{ ascii[0..ascii.len] });
-                }
-            } else if ((i + 1) == buffer.len) {
-                var x: u32 = (i + 1) % 16;
-
-                while (x < 16) : (x += 1) {
-                    try stream.writeAll("   ");
-                }
-
-                try stream.print(" {s}\n", .{ ascii[0..((i+1) % 16)] });
+        // 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");
 }
 
-// test "simple hexdump test" {
-//     print("\n\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n\n", .{});
-// 
-//     var buffer = "hello this is a simple text to print";
-//     var hexbuf: [2000]u8 = undefined;
-//     var hexfbs = std.io.fixedBufferStream(&hexbuf);
-//     var hexwriter = hexfbs.writer();
-//     try hexdump(hexwriter, "Hello World", buffer);
-//     print("{s}\n", .{hexfbs.getWritten()});
-// 
-// }
+test "36-byte hexdump test" {
+    print("\nPrint hexdump, NO AUTOMATIC VERIFICATION, READ SOURCE CODE\n", .{});
+
+    var buffer = "hello this is a simple text to print";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    var 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", .{});
+
+    var buffer = "THIS IS THE END, MY ONLY...  END";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    var 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", .{});
+
+    var buffer = "hello this is another text";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    var 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", .{});
+
+    var buffer = "h";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    var 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", .{});
+
+    var buffer = "";
+    var hexbuf: [2000]u8 = undefined;
+    var hexfbs = std.io.fixedBufferStream(&hexbuf);
+    var hexwriter = hexfbs.writer();
+    try hexdump(hexwriter, "Hello World", buffer);
+    print("{s}\n", .{hexfbs.getWritten()});
+
+}