show useful info on kernel crash screen

+

@@ -0,0 +1,15 @@
+#ifndef _CLIPPER_IO_H_
+#define _CLIPPER_IO_H_
+
+#include <stdint.h>
+
+inline void outb(uint16_t port, uint8_t val) {
+	asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port) : "memory");
+}
+
+inline uint8_t peek(void* addr) {
+	uint8_t val;
+	asm volatile ("mov [%addr], %%eax" : : "m"(addr) : "eax");
+}
+
+#endif // _CLIPPER_IO_H_

src/kernel/include/internal/io.h

@@ -7,4 +7,9 @@ inline void outb(uint16_t port, uint8_t val) {
 	asm volatile ("outb %0, %1" : : "a"(val), "Nd"(port) : "memory");
 }
 
+inline uint8_t peek(void* addr) {
+	uint32_t ret = 3;
+    return ret;
+}
+
 #endif // _CLIPPER_IO_H_

src/kernel/lib/havarie.c

@@ -1,6 +1,8 @@
 #include "internal/havarie.h"
 
 #include "internal/text_screen.h"
+#include "stdlib.h"
+#include "string.h"
 
 void capsize() {
 	print_havarie_msg();
@@ -11,6 +13,73 @@ void capsize() {
 	for(;;);
 }
 
+static inline 
+uint8_t peek(void* addr) {
+	uint32_t ret;
+    asm ( "push %%fs\n\t"
+    	  "mov  $0, %%eax\n\t"
+          "mov  %%ax, %%fs\n\t"
+          "mov  %%fs:(%1), %0\n\t"
+          "pop  %%fs"
+          : "=r"(ret) : "r"(addr) );
+    return ret;
+}
+
+static
+void dump_stack(uint8_t col, uint8_t row) {
+	tscursor_set(col, row);
+	tsputs("Stack dump", TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_LIGHT_BLUE);
+	row++;
+
+	tscursor_set(col, row);
+	tsputs("          0  1  2  3   4  5  6  7   8  9  A  B   C  D  E  F", TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_GRAY);
+	row++;
+
+	int esp, ebp;
+	asm("mov %%esp, %[esp]\n"
+		"mov %%ebp, %[ebp]\n"
+		: [esp]"=m" (esp), [ebp]"=m" (ebp)
+	);
+
+	int start_address = esp & ~0xF;
+	char tmp[16];
+	for (int table_row = 0; table_row < 16; table_row++) {
+		tscursor_set(col, row);
+		
+		itoa(start_address, tmp, 16);
+		size_t len = strlen(tmp);
+
+		char* src = tmp + len - 1;
+		char* dst = tmp + 7;
+
+		if (len < 9) {
+			do {
+				*dst-- = *src--;	
+			} while(src >= tmp);
+
+			do {
+				*dst-- = '0';	
+			} while (src != dst);
+		}
+
+		tsputs(tmp, TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_GRAY);
+		tsprintf("  ");
+
+		for (int table_col = 0; table_col < 4; table_col++) {
+			uint8_t x = peek((void*)(long)(start_address + 4 * table_col + 0));
+			uint8_t y = peek((void*)(long)(start_address + 4 * table_col + 1));
+			uint8_t z = peek((void*)(long)(start_address + 4 * table_col + 2));
+			uint8_t w = peek((void*)(long)(start_address + 4 * table_col + 3));
+
+			tsprintf("%02x %02x %02x %02x  ", x, y, z, w);
+		}
+
+		row++;
+
+		start_address -= 0x10;
+	}
+}
+
 void print_havarie_msg() {
 	tsclear_screen();
 	tscursor_set(0, 0);
@@ -30,8 +99,24 @@ void print_havarie_msg() {
 		  [esi]"=m" (esi), [edi]"=m" (edi), [esp]"=m" (esp), [ebp]"=m" (ebp)
 	);
 
-	tsprintf("eax=0x%08x\t\tesi=0x%08x\n", eax, esi);
-	tsprintf("ebx=0x%08x\t\tedi=0x%08x\n", ebx, edi);
-	tsprintf("ecx=0x%08x\t\tesp=0x%08x\n", ecx, esp);
-	tsprintf("edx=0x%08x\t\tebp=0x%08x\n", edx, ebp);
+	tsputs("Registers\n", TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_LIGHT_BLUE);
+	tsprintf("eax=0x%08x\nebx=0x%08x\necx=0x%08x\nedx=0x%08x\n\n", eax, ebx, ecx, edx);
+	tsprintf("esi=0x%08x\nedi=0x%08x\nesp=0x%08x\nebp=0x%08x\n\n", esi, edi, esp, ebp);
+
+	short cs, ds, es, ss, fs, gs;
+	asm("mov %%cs, %[cs]\n"
+		"mov %%ds, %[ds]\n"
+		"mov %%es, %[es]\n"
+		"mov %%ss, %[ss]\n"
+		"mov %%fs, %[fs]\n"
+		"mov %%gs, %[gs]\n"
+		: [cs]"=m" (cs), [ds]"=m" (ds), [es]"=m" (es),
+		  [ss]"=m" (ss), [fs]"=m" (fs), [gs]"=m" (gs)
+	);
+
+	tsputs("\nSegments\n", TEXT_SCREEN_BG_BLACK | TEXT_SCREEN_FG_LIGHT_BLUE);
+	tsprintf("cs=%08x\nds=%08x\nes=%08x\n\n", cs, ds, es);
+	tsprintf("ss=%08x\nfs=%08x\ngs=%08x\n\n", ss, fs, gs);
+
+	dump_stack(18, 3);
 }

src/kernel/lib/text_screen.c

@@ -121,8 +121,6 @@ const char* decode_format_specifier_field_width(const char* str, struct printf_f
 
 		tmp[i] = *str++;
 	}
-	tmp[0] = '8';
-	tmp[1] = 0;
 	tmp[i] = '\0';
 
 	data->field_size = atoi(tmp);