From eafeeb6432963ff18f0f1e0700722d819a0340b1 Mon Sep 17 00:00:00 2001
From: kudasai <47227786+kudasaixc@users.noreply.github.com>
Date: Sun, 5 Jul 2026 15:09:54 +0200
Subject: [PATCH] feat(shell): add hexdump command for hex + ASCII memory views

hexdump <hex address> <length> dumps a memory range as a classic
offset / hex / ASCII table, 16 bytes per row. It complements peek
(single byte) and memdump (PMM bitmap) with the memory view you
actually want when inspecting the heap, page tables or the VGA
buffer. Reuses htoi for the address, atoi for the length, and the
terminal print helpers.

Example: hexdump B8000 48 shows the VGA text buffer.
---
 src/kernel/shell.c | 47 +++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 46 insertions(+), 1 deletion(-)

diff --git a/src/kernel/shell.c b/src/kernel/shell.c
index 575ab67..63310da 100644
--- a/src/kernel/shell.c
+++ b/src/kernel/shell.c
@@ -61,6 +61,41 @@ void print_unit(uint32_t val, const char *unit, int new_line) {
     terminal_writestring("\n");
 }
 
+// Print a single byte as two uppercase hex digits
+static void print_hex_byte(uint8_t b) {
+  const char *hex = "0123456789ABCDEF";
+  terminal_putchar(hex[(b >> 4) & 0xF]);
+  terminal_putchar(hex[b & 0xF]);
+}
+
+// Dump `len` bytes starting at `addr` as an offset / hex / ASCII table,
+// 16 bytes per row (classic hexdump -C layout).
+static void hexdump(uint32_t addr, uint32_t len) {
+  volatile uint8_t *mem = (volatile uint8_t *) addr;
+
+  for (uint32_t i = 0; i < len; i += 16) {
+    terminal_print_hex(addr + i);
+    terminal_writestring("  ");
+
+    for (uint32_t j = 0; j < 16; j++) {
+      if (i + j < len) {
+        print_hex_byte(mem[i + j]);
+        terminal_putchar(' ');
+      }
+      else {
+        terminal_writestring("   ");
+      }
+    }
+
+    terminal_writestring(" |");
+    for (uint32_t j = 0; j < 16 && i + j < len; j++) {
+      uint8_t c = mem[i + j];
+      terminal_putchar((c >= 32 && c < 127) ? (char) c : '.');
+    }
+    terminal_writestring("|\n");
+  }
+}
+
 void debug_trigger_page_fault(void) {
   terminal_writestring("\n");
   KINFO("[TEST] Attempting to read unmapped memory at 10 MB...");
@@ -93,6 +128,7 @@ static void shell_execute(char *cmd) {
     terminal_writestring("mia     - force a Page Fault for MMU testing\n");
     terminal_writestring("mmap    - print current virtual memory mappings\n");
     terminal_writestring("peek    - read and print memory at a given hex address\n");
+    terminal_writestring("hexdump - dump a memory range as hex + ASCII\n");
     terminal_writestring("echo    - repeats your input to the console\n");
     terminal_writestring("crash   - make the machine freeze (fun cmd)\n\n");
   }
@@ -247,7 +283,16 @@ static void shell_execute(char *cmd) {
   else if (strcmp(cmd_name, "peek") == 0) {
     uint32_t addr = htoi(args[1]);
     mmu_debug_peek(addr);
-	
+
+  }
+  else if (strcmp(cmd_name, "hexdump") == 0) {
+    if (argc != 3) {
+      terminal_writestring("usage: hexdump <hex address> <length>\n");
+      return;
+    }
+    uint32_t addr = htoi(args[1]);
+    uint32_t len = atoi(args[2]);
+    hexdump(addr, len);
   }
   else if (strcmp(cmd_name, "memtest") == 0) {
     char *a = malloc(32);