From 43278fb351ec5af19b89f11ace098b70aa16534e Mon Sep 17 00:00:00 2001
From: Robert <robert.altner@einweckglas.com>
Date: Tue, 5 Sep 2023 23:48:55 +0200
Subject: [PATCH] add basic kernel crash screen

---
 src/kernel/include/internal/havarie.h     |  7 +++++
 src/kernel/include/internal/text_screen.h |  3 ++
 src/kernel/kmain.c                        |  4 +++
 src/kernel/lib/havarie.c                  | 37 +++++++++++++++++++++++
 src/kernel/lib/text_screen.c              | 13 +++++++-
 5 files changed, 63 insertions(+), 1 deletion(-)
 create mode 100644 src/kernel/include/internal/havarie.h
 create mode 100644 src/kernel/lib/havarie.c

diff --git a/src/kernel/include/internal/havarie.h b/src/kernel/include/internal/havarie.h
new file mode 100644
index 0000000..645b0c9
--- /dev/null
+++ b/src/kernel/include/internal/havarie.h
@@ -0,0 +1,7 @@
+#ifndef _CLIPPER_HAVARIE_H_
+#define _CLIPPER_HAVARIE_H_
+
+void capsize() __attribute__((noreturn));
+void print_havarie_msg();
+
+#endif // _CLIPPER_HAVARIE_H_
diff --git a/src/kernel/include/internal/text_screen.h b/src/kernel/include/internal/text_screen.h
index 2a0d209..a980c47 100644
--- a/src/kernel/include/internal/text_screen.h
+++ b/src/kernel/include/internal/text_screen.h
@@ -33,6 +33,9 @@ enum text_screen_attribute {
 
 void tsinit(void);
 
+void tsclear_screen();
+void tscursor_set(uint8_t x, uint8_t y);
+
 void tsputch(char ch, uint8_t color);
 void tsputs(const char* str, uint8_t color);
 
diff --git a/src/kernel/kmain.c b/src/kernel/kmain.c
index 9ca34e1..6297914 100644
--- a/src/kernel/kmain.c
+++ b/src/kernel/kmain.c
@@ -3,6 +3,8 @@
 #include <stddef.h>
 #include <stdint.h>
 
+#include "internal/havarie.h"
+
 #if defined(__linux__)
 #	error "Please use a platform agnostic compiler"
 #endif
@@ -21,5 +23,7 @@ void kmain(void) {
 
 	tsprintf("Test | Integers: %d, Unsigned: %u, Hexadecimal: %x\n", -48, 28493, 28493);
 
+	capsize();
+
 	return;
 }
diff --git a/src/kernel/lib/havarie.c b/src/kernel/lib/havarie.c
new file mode 100644
index 0000000..ed3ffd6
--- /dev/null
+++ b/src/kernel/lib/havarie.c
@@ -0,0 +1,37 @@
+#include "internal/havarie.h"
+
+#include "internal/text_screen.h"
+
+void capsize() {
+	print_havarie_msg();
+
+	asm("cli\n"
+		"hlt");
+
+	for(;;);
+}
+
+void print_havarie_msg() {
+	tsclear_screen();
+	tscursor_set(0, 0);
+	tsputs("Havarie - the clipper has capsized\n\n\n", TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_LIGHT_CYAN);
+
+	
+	int eax, ebx, ecx, edx, esi, edi, esp, ebp;
+	asm("mov %%eax, %[eax]\n"
+		"mov %%ebx, %[ebx]\n"
+		"mov %%ecx, %[ecx]\n"
+		"mov %%edx, %[edx]\n"
+		"mov %%esi, %[esi]\n"
+		"mov %%edi, %[edi]\n"
+		"mov %%esp, %[esp]\n"
+		"mov %%ebp, %[ebp]\n"
+		: [eax]"=m" (eax), [ebx]"=m" (ebx), [ecx]"=m" (ecx), [edx]"=m" (edx), 
+		  [esi]"=m" (esi), [edi]"=m" (edi), [esp]"=m" (esp), [ebp]"=m" (ebp)
+	);
+
+	tsprintf("eax=0x%x\t\tesi=0x%x\n", eax, esi);
+	tsprintf("ebx=0x%x\t\tedi=0x%x\n", ebx, edi);
+	tsprintf("ecx=0x%x\t\tesp=0x%x\n", ecx, esp);
+	tsprintf("edx=0x%x\t\tebp=0x%x\n", edx, ebp);
+}
diff --git a/src/kernel/lib/text_screen.c b/src/kernel/lib/text_screen.c
index 6481ae9..3c033ec 100644
--- a/src/kernel/lib/text_screen.c
+++ b/src/kernel/lib/text_screen.c
@@ -28,6 +28,17 @@ void tsinit(void) {
 	outb(0x3D5, 0x20);
 }
 
+void tsclear_screen() {
+	for (uint32_t i = 0; i < ((SCREEN_WIDTH * SCREEN_HEIGHT) >> 2); i++) {
+		((uint32_t*)videomem)[i] = (uint32_t)0;
+	}
+}
+
+void tscursor_set(uint8_t x, uint8_t y) {
+	cursor_x = x;
+	cursor_y = y;
+}
+
 void tsputch(char ch, uint8_t color) {
 	const char tmp[2] = { ch, 0 };
 	tsputs(tmp, color);
@@ -46,7 +57,7 @@ void handle_special_char(char c) {
 		} break;
 
 		case '\r': cursor_x = 0; break;
-		case '\t': cursor_x += 4; break;
+		case '\t': cursor_x += 4; cursor_x -= cursor_x % 4; break;
 	}
 }