kernel tools split into kio (for i/o) and kttools (kernel type tools).

in general, kernel libraries will be marked with "k" in the beginning.

src/kio.c

@@ -0,0 +1,61 @@
+#include "kio.h"
+#include <stddef.h>
+
+/*
+ * VARS
+ */
+
+int cursor_col = 0;
+int cursor_row = 0;
+volatile uint16_t* const vga_buffer = (uint16_t*)0xB8000;
+uint16_t vga_attributes = 0x0F00;
+
+/*
+ * FUNCTIONS
+ */
+
+void vga_clear() {
+	for (int col = 0; col < VGA_GRID_COLS; col ++) {
+		for (int row = 0; row < VGA_GRID_ROWS; row ++) {
+            //works out to iterating every cell
+			const size_t index = (VGA_GRID_COLS * row) + col;
+            //vga buffer looks something like xxxxyyyyzzzzzzzz
+            //x=bg color
+            //y=fg color
+            //c=character to use
+            //Therefore, to write, we just take our color data and tack on the character to the end.
+			vga_buffer[index] = vga_attributes | ' '; //blank out
+		}
+	}
+}
+
+void vga_putc(char c)
+{
+    //Check for some freaky escape character first
+    if(c == '\n') {
+        cursor_col = 0;
+        cursor_row = (cursor_row + 1) % 25;
+        return;
+    }
+        //Calculate where in the vga buffer to put the character
+		const size_t index = (VGA_GRID_COLS * cursor_row) + cursor_col;
+        //VGA buffer cell consists of the first half attributes, second half character
+		vga_buffer[index] = vga_attributes | c;
+		cursor_col++;
+}	
+
+void vga_set_attributes(uint8_t attributes) {
+     vga_attributes = ((uint16_t)attributes) << 8;
+}
+
+
+void vga_print(const char* out)
+{
+	for (int i = 0; out[i] != '\0'; i++)
+        vga_putc(out[i]);
+}
+
+void vga_println(const char* out) {
+    vga_print(out);
+    vga_print("\n");
+}

src/kttools.c

@@ -0,0 +1,52 @@
+#include "kttools.h"
+#include <stdint.h>
+/*
+ * VARS
+ */
+
+//Placeholder.
+
+/*
+ * FUNCTIONS
+ */
+
+
+//convert digits from int num to buffer buf. in hex. This is 32 bit only for now!
+//WARN: integer is written from right to left into the buffer, and will halt if the buffer is too small.
+
+/**
+ * @brief Convert a hex int to string, up to 32 bits.
+ *
+ *  Converts int "num" into a null-terminated string, placed into buffer "buf".
+ *  Evaluates from right to left, so left hand digits will be cut off if the buffer is too small
+ *  Should work for non 32-bit integers actually, but is uint32_t for now.
+ *  
+ *  @param  num:    Value to convert to string
+ *  @param  buf:    Memory to place the string into
+ *  @param  size:   Size of the memory buffer
+ *
+ *  @return No return value
+ *
+ */
+void i_to_str(uint32_t num, char* buf, int size) {
+    //null terminate the string
+    buf[--size] = '\0';
+    while(size > 0 && (num) != 0){
+        int isolated_num = num % 0x10;
+        if(isolated_num > 9){
+            isolated_num+=7;
+        }
+        buf[--size] = '0' + isolated_num;
+        num/=0x10;
+    }
+
+    //now shift the whole thing to the left
+    if(size != 0) {
+        while(buf[size]!='\0') {
+            *buf = buf[size];
+            buf++;
+        } 
+        *buf = '\0'; 
+    }
+}
+

src/main.c

@@ -1,43 +1,29 @@
 //Our own code, at this point...
 //#include <stddef.h>
 #include <stdint.h>
-#include "kernio.h"
-
-//convert digits from int num to buffer buf. in hex. This is 32 bit only for now!
-//WARN: integer is written from right to left into the buffer, and will halt if the buffer is too small.
-void i_to_str(uint32_t num, char* buf, int size) {
-    //null terminate the string
-    buf[--size] = '\0';
-    while(size > 0 && (num) != 0){
-        int isolated_num = num % 0x10;
-        if(isolated_num > 9){
-            isolated_num+=7;
-        }
-        buf[--size] = '0' + isolated_num;
-        num/=0x10;
-    }
-
-    //now shift the whole thing to the left
-    if(size != 0) {
-        while(buf[size]!='\0') {
-            *buf = buf[size];
-            buf++;
-        } 
-        *buf = '\0'; 
-    }
-}
+#include "kio.h"
+#include "kttools.h"
 
+typedef struct {
+    uint32_t flags;
+    uint32_t mem_lower;
+    uint32_t mem_upper;
+    uint32_t boot_device;
+    uint32_t cmdline;
+    uint32_t mods_count;
+    uint32_t mods_addr;
+} multiboot_info_t;
 
 //finally, main.
-void kern_main()
+void kern_main(uint32_t multiboot_magic, multiboot_info_t* multiboot_info)
 {
-
     //wipe the screen
 	vga_clear();
 
 	//IT IS TIME. TO PRINT.
-    char lol[5];
-    i_to_str(0xCAFEBABE, lol, 5); 
+    char lol[9];
+    i_to_str(multiboot_info->mem_upper, lol, 9); 
+
 	vga_println(lol);
 }
 

src/start.s

@@ -36,7 +36,8 @@
     start:
 		//Lets set up the stack. Stack grows downward on x86. We did the work earlier of defining where the top of the stack is, so just tell esp.
         mov $stack_top, %esp //set the stack pointer
-		
+	    pushl %ebx
+        pushl %eax
         //To C-land!
         call kern_main