From 39f8c5fc48c69128a8fc1558eef9d8c9a0787779 Mon Sep 17 00:00:00 2001
From: DualFroz <me@dualfroz.com>
Date: Mon, 24 Aug 2026 09:48:49 +0200
Subject: [PATCH] feat(drivers): add kprintf console over serial

---
 include/console.h |  10 ++++
 src/console.c     | 123 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 133 insertions(+)
 create mode 100644 include/console.h
 create mode 100644 src/console.c

diff --git a/include/console.h b/include/console.h
new file mode 100644
index 0000000..1dca65c
--- /dev/null
+++ b/include/console.h
@@ -0,0 +1,10 @@
+#ifndef FROSTBYTE_CONSOLE_H
+#define FROSTBYTE_CONSOLE_H
+
+#include "types.h"
+
+void consoleInit(void);
+void kputchar(char c);
+void kprintf(const char* format, ...);
+
+#endif
diff --git a/src/console.c b/src/console.c
new file mode 100644
index 0000000..1d316cc
--- /dev/null
+++ b/src/console.c
@@ -0,0 +1,123 @@
+#include "console.h"
+#include "vga.h"
+#include "serial.h"
+#include "ports.h"
+#include <stdarg.h>
+
+void consoleInit(void)
+{
+    serialInit();
+    vgaInit();
+}
+
+void kputchar(char c)
+{
+    serialWrite(c);
+    vgaPutChar(c);
+}
+
+static void writeString(const char* str)
+{
+    while (*str)
+        kputchar(*str++);
+}
+
+static void writeUnsigned(uint64 value, uint32 base, bool upper, int minWidth, char pad)
+{
+    static const char* lower = "0123456789abcdef";
+    static const char* higher = "0123456789ABCDEF";
+    const char* digits = upper ? higher : lower;
+    char buffer[32];
+    int length = 0;
+
+    if (value == 0)
+        buffer[length++] = '0';
+    while (value > 0) {
+        buffer[length++] = digits[value % base];
+        value /= base;
+    }
+    while (length < minWidth)
+        buffer[length++] = pad;
+
+    while (length > 0)
+        kputchar(buffer[--length]);
+}
+
+static void writeSigned(int64 value)
+{
+    if (value < 0) {
+        kputchar('-');
+        writeUnsigned((uint64)(-value), 10, false, 0, ' ');
+    } else {
+        writeUnsigned((uint64)value, 10, false, 0, ' ');
+    }
+}
+
+void kprintf(const char* format, ...)
+{
+    uint64 flags = saveAndDisableInterrupts();
+
+    va_list args;
+    va_start(args, format);
+
+    for (usize i = 0; format[i]; i++) {
+        if (format[i] != '%') {
+            kputchar(format[i]);
+            continue;
+        }
+
+        i++;
+        int width = 0;
+        char pad = ' ';
+        if (format[i] == '0') {
+            pad = '0';
+            i++;
+        }
+        while (format[i] >= '0' && format[i] <= '9') {
+            width = width * 10 + (format[i] - '0');
+            i++;
+        }
+
+        int longCount = 0;
+        while (format[i] == 'l') {
+            longCount++;
+            i++;
+        }
+
+        switch (format[i]) {
+        case 'c':
+            kputchar((char)va_arg(args, int));
+            break;
+        case 's':
+            writeString(va_arg(args, const char*));
+            break;
+        case 'd':
+        case 'i':
+            writeSigned(longCount ? va_arg(args, int64) : (int64)va_arg(args, int));
+            break;
+        case 'u':
+            writeUnsigned(longCount ? va_arg(args, uint64) : (uint64)va_arg(args, uint32), 10, false, width, pad);
+            break;
+        case 'x':
+            writeUnsigned(longCount ? va_arg(args, uint64) : (uint64)va_arg(args, uint32), 16, false, width, pad);
+            break;
+        case 'X':
+            writeUnsigned(longCount ? va_arg(args, uint64) : (uint64)va_arg(args, uint32), 16, true, width, pad);
+            break;
+        case 'p':
+            writeString("0x");
+            writeUnsigned((uint64)va_arg(args, void*), 16, false, 16, '0');
+            break;
+        case '%':
+            kputchar('%');
+            break;
+        default:
+            kputchar('%');
+            kputchar(format[i]);
+            break;
+        }
+    }
+
+    va_end(args);
+    restoreInterrupts(flags);
+}