basickernel/boot/print32.asm

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2018-02-23 16:20:31 +00:00
[bits 32]
VIDEO_MEMORY: equ 0xB8000
WHITE_ON_BLACK: equ 0x0F
;;;
; print_string_pm
; ------------
; Print a string stored in memory.
;
; Parameters:
; - ebx: pointer to string in memory
print_string_pm:
pusha
mov edx, VIDEO_MEMORY ; set `edx' to the start of the video memory
print_string_pm_loop:
mov al, [ebx] ; store the char at `ebx' in `al'
mov ah, WHITE_ON_BLACK ; store the attributes in `ah'
cmp al, 0 ; if null-termination then done
je print_string_pm_done
mov [edx], ax ; store char and attributes
add ebx, 1 ; increment ebx to next char
add edx, 2 ; increment to next char cell in vidmem
jmp print_string_pm_loop
print_string_pm_done:
popa
ret