merging from remote

Mainly adding support in write_cell() to use logical character indexes vs direct memory offsets

.gitignore

@@ -1,5 +1,5 @@
 *bochslog*
-*.o
-*.elf
-./*o
-./*elf
+*o
+*elf
+*iso
+*swp

framebuffer.c

@@ -0,0 +1,35 @@
+// Driver implementation for Jank's text frame buffer
+
+// Buffer can display 80 columns by 25 Rows
+// Start of buffer is at (real)address 0x000B8000
+// Memory at this section is divided into 16-bit cells 
+    // | 15-8 | 7-4 | 0-3
+    // | Asci | FG  | BG
+#include "framebuffer.h"
+
+static char* Frame_Buffer = (char*)FRAME_BUFFER_ADDR;
+static char* Frame_Buffer_End = (char*)(FRAME_BUFFER_ADDR + AREA);
+// Writes character to a given cell in the framebuffer
+    // @cell parameter is the logical (linear)index into the buffer
+	// _not_ the actual offset from the buffer addr
+	// also proper location is caller's responsibility
+void write_cell(unsigned cell, char c, char fg, char bg) {
+    Frame_Buffer[cell*2] = c;
+    Frame_Buffer[cell+1] = (fg & 0x0f << 4) | (bg & 0x0f);
+}
+
+void clear_buffer() {
+	char* fp = Frame_Buffer;
+	while(fp!=Frame_Buffer_End) {
+		*fp = 0x00;
+	}
+}
+void print(char* str) {
+	for(unsigned i =0;i<strlen(str);i+=2) {
+		write_cell(i, str[i], Green, White);
+	}
+}
+
+void yote() {
+	print("asdf");
+}

framebuffer.h

@@ -0,0 +1,31 @@
+#include "stl/string.h"
+#define COLUMNS 80
+#define ROWS 25
+#define AREA ( COLUMNS * ROWS )
+
+
+#define FRAME_BUFFER_ADDR 0x000B8000
+#define Black 0x01
+#define Blue 0x02
+#define Green 0x03
+#define Cyan 0x04
+#define Red 0x05
+#define Magenta 0x05
+#define Brown 0x06
+#define LightGrey 0x07
+#define DarkGrey 0x08
+#define LightBlue 0x09
+#define LightGreen 0x0a
+#define LightCyan 0x0b
+#define LightRed 0x0c
+#define LightMagenta 0x0d
+#define LightBrown 0x0e
+#define White 0x0f
+
+void write_cell(unsigned cell, char c , char fg, char bg);
+
+void clear_buffer();
+
+void print(char* str);
+
+void yote();

loader.asm

@@ -5,6 +5,23 @@ MAGIC_NUMBER 	equ 0x1BADB002
 FLAGS 			equ 0x0
 CHECKSUM 		equ -MAGIC_NUMBER
 
+
+; size in bytes of stack 
+KERNEL_STACK_SIZE	equ 4096
+
+; external labels(cdecl) calling convention
+extern yote
+
+section .bss
+align 4		; aligning to bytes for x86(32-bit) reasons
+; because this is the first thing we actually do (virual)address 0x00000000 will 
+; contain 4KB of memory for our stack
+kernel_stack:
+	resb KERNEL_STACK_SIZE	; reserver bytes instruction
+	; point to what will be bottom of stack
+	; which will grow down towards (virtual)address 0x00000000
+	mov esp, kernel_stack + KERNEL_STACK_SIZE	
+
 section .text
 ; align all instructions to 4 byte boundary by the x86 instruction set law
 align 4
@@ -14,7 +31,7 @@ align 4
 	dd CHECKSUM
 
 loader:
-	
+	call yote
 .loop:
 	jmp .loop
 

makefile

@@ -1,22 +1,22 @@
-ASM=nasm
 CC=gcc
+ASM=nasm
 LINK=ld
 ISO=genisoimage
 
-all: loader link iso
-	echo 'yeeting'
-# build our loader
-loader: loader.asm
-	# loading the kernel form loader.asm
-	# creates loader.o
-	$(ASM) -f elf32 loader.asm
+OBJECTS=loader.o framebuffer.o
+AFLAGS=-f elf32
+CFLAGS=-m32 -nostdlib -nostdinc -fno-builtin -fno-stack-protector -nostartfiles \
+		-nodefaultlibs -Wall -Wextra -Werror -c
 
-# link the kernel to our loader
-link: loader.o
-	$(LINK) -T link.ld -melf_i386 loader.o -o kernel.elf
+all: kernel.elf
 
-# build the iso file into our target directory
-iso:
+# Link objects together to produce the kernel object
+kernel.elf: $(OBJECTS)
+	$(LINK) -T link.ld -melf_i386 $(OBJECTS) -o kernel.elf
+
+# Builds image of our os
+os.iso: kernel.elf
+	cp kernel.elf iso/boot/kernel.elf
 	$(ISO) -R							\
 		-b boot/grub/stage2_eltorito    \
 		-no-emul-boot                   \
@@ -27,3 +27,18 @@ iso:
 		-boot-info-table                \
 		-o os.iso                       \
 		iso
+
+# Building C objecets
+%.o: %.c
+	$(CC) $(CFLAGS) $< -o $@
+
+# Builind asm objects
+%.o: %.asm
+	$(ASM) $(AFLAGS) $< -o $@
+
+# Running (no recipes called) 
+run: os.iso
+	bochs -f bochsrc.conf -q 
+
+clean:
+	rm -rf *.o kernel.elf os.iso bochslog.txt

scripts/run.sh

@@ -0,0 +1,2 @@
+#!/zsh
+bochs -f bochsrc.conf -q 

stl/string.h

@@ -0,0 +1,8 @@
+// our own stuff for stl utilities
+
+unsigned strlen(const char* str) {
+	unsigned idx = 0;
+	while(str[idx])
+		idx++;
+	return idx;
+}