3 files changed, 75 insertions, 0 deletions
diff --git a/src/common/common.asm b/src/common/common.asm
new file mode 100644
index 0000000..a98ef67
--- /dev/null
+++ b/src/common/common.asm
@@ -0,0 +1,27 @@
+;; common.asm
+%ifndef COMMON_ASM
+%define COMMON_ASM
+
+;; Real mode constants
+%define READ_SECTORS_NUM 16
+%define BOOT_LOAD_ADDR 0x7c00
+%define STAGE2_ADDR 0x7e00
+%define SECTOR_SIZE 512
+%define STACK_ADDR 0x9c00
+
+;; Mostly kernel and protected mode constants
+%define VGA_COLOR_BLACK 0
+%define VGA_COLOR_GREEN 2
+%define VGA_COLOR_RED 4
+%define VGA_WHITE_ON_BLACK 0x0f20
+%define VGA_BUFFER 0xb8000
+%define VGA_SCREEN_X 80
+%define VGA_SCREEN_Y 25
+%define VGA_SCREEN (VGA_SCREEN_X*VGA_SCREEN_Y)
+
+;; Forth-specific constants
+%define FS_DATA_STACK 0x80000
+%define FS_RET_STACK 0x90000
+%define FS_DICT_BASE 0xa0000
+
+%endif
diff --git a/src/common/common.protmode.clear.asm b/src/common/common.protmode.clear.asm
new file mode 100644
index 0000000..47cb980
--- /dev/null
+++ b/src/common/common.protmode.clear.asm
@@ -0,0 +1,13 @@
+;; common.protmode.print.asm
+
+%include "common.asm"
+
+_clear_screen:  
+        mov edi, VGA_BUFFER
+        mov ecx, VGA_SCREEN
+        mov ax, VGA_WHITE_ON_BLACK
+.clear:
+        mov [edi], eax
+        add edi, 2
+        loop .clear
+        ret
diff --git a/src/common/common.protmode.print.asm b/src/common/common.protmode.print.asm
new file mode 100644
index 0000000..5995e69
--- /dev/null
+++ b/src/common/common.protmode.print.asm
@@ -0,0 +1,35 @@
+;; common.protmode.print.asm
+
+%include "common.asm"
+
+_print_string_pm_vga:   
+        pusha
+        mov edi, VGA_BUFFER
+        mov ah, WB_COLOR
+        xor ecx, ecx
+        xor edx, edx
+
+.print_loop:
+        lodsb
+        test al, al
+        jz .done
+
+        push eax
+        mov eax, edx
+        imul eax, eax, 160
+        lea edi, [VGA_BUFFER + eax]
+        lea edi, [edi + ecx * 2]
+        pop eax
+        
+;; Advance cursor
+        inc cl
+        cmp cl, 80
+        jb .print_loop
+        xor cl, cl
+        inc dl
+
+        jmp .print_loop
+        
+.done:
+        popa
+        ret