;=----------------------------------------------------------------------------=;
;                            GNU GPL OS/K                                      ;
;                                                                              ;
;   Authors: spectral`                                                         ;
;            NeoX                                                              ;
;                                                                              ;
;   Desc:   Kernel (second stage) Loader for OS/K INCLUDED FUNCTIONS           ;
;                  (x86_64 architecture only)                                 ;
;=----------------------------------------------------------------------------=;

[BITS 64]

clear:
;-----------------------------------------------------------------------;
; x64/LM Clear Text Screen Function                                     ;
;-----------------------------------------------------------------------;
    mov qword [NextTRAM], TRAM
    mov edi, TRAM
    push rsi
    push rdi
    push rcx
    mov ah, 0
    mov al, 0
    mov rcx, 0x4000                         ; traditionnal value
    rep stosw                               ; fill screen with al while cx > 0
    pop rcx
    pop rsi
    pop rdi
    ret

write:
;-----------------------------------------------------------------------;
; x64/LM Text Printing Functions                                        ;
; bl  : color code                                                      ;
; esi : string address                                                  ;
;-----------------------------------------------------------------------;
    mov  edi, [NextTRAM]                     ; TRAM ADDRESS
    push rsi
    push rdi
.pLoop:
    lodsb
    cmp al, 0                               ; while @al, i.e. while we're not hitting '\0'
    je .pEnd                                
    cmp al, 0x0A                            ; LF
    je .lf
    cmp al, 0x0D                            ; CR
    je .cr
    stosb                                   ; text subpixel
    mov al, bl
    stosb                                   ; color subpixel
    add qword [NextTRAM], 0x2               ; Cursor moving
    add qword [VGA_X], 0x2                  ; coord + 2 because 2 subpixels
    jmp .pLoop
.pEnd:    
    pop rdi
    pop rsi    
    ret
.lf:
    mov rax, [VGA_HEIGHT64]
    add [NextTRAM], rax                     ; Cursor moving
    add [NextTRAM], rax
    add edi, eax                            ; Address moving
    add edi, eax
    jmp .pLoop
.cr:
    push rax
    mov rax, qword [VGA_X]
    sub qword [NextTRAM], rax               ; pos = X + Y * VGA_HEIGHT64. Donc pos - X = début de ligne
    sub edi, edx
    mov qword [VGA_X], 0
    pop rax
    jmp .pLoop
.scroll:
    ; XXX ;
    jmp .pLoop