From 9b8698769535846d029c44247956eed9a21f1185 Mon Sep 17 00:00:00 2001
From: Marvin Borner
Date: Sun, 4 Jul 2021 21:31:28 +0200
Subject: Initial commit

---
 src/loader/log.c | 108 +++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 108 insertions(+)
 create mode 100644 src/loader/log.c

(limited to 'src/loader/log.c')

diff --git a/src/loader/log.c b/src/loader/log.c
new file mode 100644
index 0000000..a2c05f0
--- /dev/null
+++ b/src/loader/log.c
@@ -0,0 +1,108 @@
+#include <cpu.h>
+#include <lib.h>
+#include <log.h>
+
+/**
+ * Formatting
+ */
+
+static u32 vsnprintf(char *str, u32 size, const char *format, va_list ap)
+{
+	u32 length = 0;
+
+	int temp_int;
+	char temp_ch;
+	char *temp_str;
+
+	char buffer[64] = { 0 };
+
+	// TODO: Fix potential memory overflows because of str[length++]=xxx
+	char ch;
+	while ((ch = *format++)) {
+		if (ch == '%') {
+			switch (*format++) {
+			case '%':
+				str[length++] = '%';
+				break;
+			case 'c':
+				temp_ch = va_arg(ap, int);
+				str[length++] = temp_ch;
+				break;
+			case 's':
+				temp_str = va_arg(ap, char *);
+				length += strlcpy(&str[length], temp_str, size - length);
+				break;
+			case 'b':
+				temp_int = va_arg(ap, int);
+				itoa(temp_int, buffer, 2);
+				length += strlcpy(&str[length], buffer, size - length);
+				break;
+			case 'd':
+				temp_int = va_arg(ap, int);
+				itoa(temp_int, buffer, 10);
+				length += strlcpy(&str[length], buffer, size - length);
+				break;
+			case 'x':
+				temp_int = va_arg(ap, int);
+				itoa(temp_int, buffer, 16);
+				length += strlcpy(&str[length], buffer, size - length);
+				break;
+			default:
+				serial_print("Unknown printf format\n");
+			}
+		} else {
+			str[length++] = ch;
+		}
+	}
+
+	return length;
+}
+
+/**
+ * Serial
+ */
+
+void serial_install(void)
+{
+	outb(0x3f8 + 1, 0x00);
+	outb(0x3f8 + 3, 0x80);
+	outb(0x3f8 + 0, 0x03);
+	outb(0x3f8 + 1, 0x00);
+	outb(0x3f8 + 3, 0x03);
+	outb(0x3f8 + 2, 0xc7);
+	outb(0x3f8 + 4, 0x0B);
+}
+
+static int is_transmit_empty(void)
+{
+	return inb(0x3f8 + 5) & 0x20;
+}
+
+static void serial_put(char ch)
+{
+	while (is_transmit_empty() == 0)
+		;
+	outb(0x3f8, (u8)ch);
+}
+
+void serial_print(const char *data)
+{
+	for (const char *p = data; *p; p++)
+		serial_put(*p);
+}
+
+/**
+ * Universal print function
+ */
+
+void log(const char *format, ...)
+{
+	char buf[1024] = { 0 };
+
+	va_list ap;
+	va_start(ap, format);
+	vsnprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+
+	serial_print(buf);
+}
-- 
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