;=----------------------------------------------------------------------------=;
;                            GNU GPL OS/K                                      ;
;                                                                              ;
;   Authors: spectral`                                                         ;
;            NeoX                                                              ;
;                                                                              ;
;   Desc:   Basic Read Only ATA Long mode Driver                               ;
;                   (x86_64 architecture only)                                 ;
;=----------------------------------------------------------------------------=;

[BITS 64]

;; BPB
%define OEMName           bp+0x03           ; Disk label
%define bytesPerSector    bp+0x0b           ; Bytes per sector
%define sectorsPerCluster bp+0x0d           ; Sectors per cluster
%define reservedSectors   bp+0x0e           ; Reserved sectors
%define fats              bp+0x10           ; Number of fats
%define rootDirEntries    bp+0x11           ; Number of entries in root dir
%define sectors           bp+0x13           ; Logical sectors
%define mediaType         bp+0x15           ; Media descriptor byte
%define fatSectors        bp+0x16           ; Sectors per FAT
%define sectorsPerTrack   bp+0x18           ; Sectors per track
%define heads             bp+0x1a           ; Number of sides/heads
%define hiddenSectors     bp+0x1c           ; Hidden sectors
%define hugeSectors       bp+0x20           ; LBA sectors
%define biosBootdrvNum    bp+0x24           ; Bootdrv number
%define reserved          bp+0x25           ; This is not used
%define bootSignature     bp+0x26           ; Bootdrv signature
%define volumeId          bp+0x27           ; Volume ID
%define volumeLabel       bp+0x2b           ; Volume Label
%define fatTypeLabel      bp+0x36           ; File system type

;; GLOBAL DATA

Bootdrv         db  0
end             db "[End of Sector]", 0x0
buffer:         times 513 db "_"

;; TEXT

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, 0x1f6                            ; Drive and head port
    mov al, 0x0a0                            ; Drive 0, head 0
    out dx,al

    mov dx, 0x1f2                            ; Sector count port
    mov al, 1                                ; Read one sector
    out dx, al

    mov dx, 0x1f3                            ; Sector number port
    mov al, 1                                ; Read sector one
    out dx, al

    mov dx, 0x1f4                            ; Cylinder low port
    mov al, 0                                ; Cylinder 0
    out dx, al

    mov dx, 0x1f5                            ; Cylinder high port
    mov al, 0                                ; The rest of the cylinder 0
    out dx, al

    mov dx, 0x1f7                            ; Command port
    mov al, 0x20                             ; 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 because it copies words
    mov rdi, buffer
    mov dx, 0x1f0                            ; 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