#generate 16-bit code
.code16

#hint the assembler that here is the executable code located
.text
.globl _start;
#boot code entry
_start:
  jmp _boot
start: .asciz "Start.\n\r"
error: .asciz "Error.\n\r"
succes: .asciz "Succes.\n\r"
ffs: .asciz "F.\n\r"
end: .asciz "End.\n\r"
    
.macro mWriteString str              #macro which calls a function to print a string
  leaw  \str, %si
  call .writeStringIn
.endm

# function to print the string
.writeStringIn:
    lodsb
    orb  %al, %al
    jz   .writeStringOut
    movb $0x0e, %ah
    int  $0x10
    jmp  .writeStringIn
  .writeStringOut:
ret
  

_boot:
  mWriteString start
  
  #This goes first as to now overwrite %ah and %al.
  mov $0x00, %ax
  mov %ax, %es #Section to write into
  
  mov $0x02, %ah # Read sectors from drive
  mov $0x01, %al # Number of sectors to read
  mov $0x00, %ch # Low 8 bits of cylinder
  mov $0x02, %cl # First sector to read (bits 0-5), upper bits of cylinder (bits 6-7)
  mov $0x00, %dh # Head number
  mov $0x00, %dl # Drive number
#  mov $0x00, %es
  mov $0xFF, %bx #Offset into section
  int $0x13 # Low level disk services
  
  jnc notcarry
  mWriteString error
  jmp endcarrycheck
  
  notcarry:
  mWriteString succes
  #fallthrough
  
  endcarrycheck:
  
  mWriteString mystr
  
  mWriteString end
  
  #



#move to 510th byte from the start and append boot signature
. = _start + 510
.byte 0x55
.byte 0xaa

mystr: .asciz "asdf"

. = _start + 1023
.byte 0x00