;=----------------------------------------------------------------------------=;
;                            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 I don't think I'll implement this, but never know...;
    jmp .pLoop
    
dump:
;-----------------------------------------------------------------------;
; x64/LM Dump Printing Functions                                        ;
; bl  : color code                                                      ;
; esi : string address                                                  ;
;-----------------------------------------------------------------------;
    mov  edi, [NextTRAM]                     ; TRAM ADDRESS
    push rsi
    push rdi
    push rcx
    mov rcx, 512
.pLoop:
    lodsb                   
    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
    loop .pLoop
    pop rcx
    pop rdi
    pop rsi    
    ret

ata_read:
;-----------------------------------------------------------------------;
; x64/LM ATA Reading function                                           ;
;                                                                       ;
;                                                                       ;
;-----------------------------------------------------------------------;

;  Technical infos about the ports (Intel Doc):
;
;       Port   Access Mode  Misc
;
;       1f0       r/w       Data register, the bytes of the disk itself
;       1f1       r         Error register that can be handled
;       1f2       r/w       Sector count, how many sectors to read
;       1f3       r/w       Sector number, the actual sector wanted
;       1f4       r/w       Cylinder low, cylinders is 0-1024
;       1f5       r/w       Cylinder high, this makes up the rest of the 1024
;       1f6       r/w       Drive/head
;                              bit 7 = 1
;                              bit 6 = 0
;                              bit 5 = 1
;                              bit 4 = 0  drive 0 select
;                                    = 1  drive 1 select
;                              bit 3-0    head select bits
;       1f7       r         Status register
;                              bit 7 = 1  controller is executing a command
;                              bit 6 = 1  drive is ready
;                              bit 5 = 1  write fault
;                              bit 4 = 1  seek complete
;                              bit 3 = 1  sector buffer requires servicing
;                              bit 2 = 1  disk data read corrected
;                              bit 1 = 1  index - set to 1 each revolution
;                              bit 0 = 1  previous command ended in an error
;       1f7       w         Command register
;                            commands:
;                              50h format track
;                              20h read sectors with retry
;                              21h read sectors without retry
;                              22h read long with retry
;                              23h read long without retry
;                              30h write sectors with retry
;                              31h write sectors without retry
;                              32h write long with retry
;                              33h write long without retry
;

   push rax
   push rbx
   push rdx
   push rcx
   push rdi
   mov     dx,1f6h         ;Drive and head port
   mov     al,0a0h         ;Drive 0, head 0
   out     dx,al

   mov     dx,1f2h         ;Sector count port
   mov     al,1            ;Read one sector
   out     dx,al

   mov     dx,1f3h         ;Sector number port
   mov     al,1            ;Read sector one
   out     dx,al

   mov     dx,1f4h         ;Cylinder low port
   mov     al,0            ;Cylinder 0
   out     dx,al

   mov     dx,1f5h         ;Cylinder high port
   mov     al,0            ;The rest of the cylinder 0
   out     dx,al

   mov     dx,1f7h         ;Command port
   mov     al,20h          ;Read with retry.
   out     dx,al
still_going:
   in      al,dx
   test    al,8            ;This means the sector buffer requires
            ;servicing.
   jz      still_going     ;Don't continue until the sector buffer
            ;is ready.

   mov     cx,512/2        ;One sector /2
   mov     rdi,buffer
   mov     dx,1f0h         ;Data port - data comes in and out of here.
   rep     insw
   pop rdi
   pop rcx
   pop rdx
   pop rbx
   pop rax
   mov bl, 0x0F
   mov esi, buffer
   call dump
   mov bl, 0x0A
   mov esi, end
   call write
   ret
   buffer:  times 512 db "_"
   end:     db "[End of Sector]", 0x0