TASM getting next byte from buffer

Question

I am writing procedure that gets next byte from buffer and if we need more bytes when buffer is already analysed, it reads from file for more information. But it doesn't work. Don't know why at all. This function is used in loop which prints char in al register, but I don't get what I need (actually I get infinite loop, I was like wtf? Can't realise why). I think that it always performs the jump. Don't know why. Any ideas? Thank you in advance. Here is the code:

proc get_byte

  mov ah, read_buffer_length   ; read_buffer_length - actual amount of bytes read from file
  sub ah, 1                    ; subtracting one since read_position is calculated from 0
                               ; and read_buffer_length from 1
  cmp read_position, ah        ; comparing current position in buffer and buffer length
  jle @@not_less               ; if read_position <= ah then we jump to @@not_less

  @@read_input_buffer:         ; we need more bytes, since we dont have anything in buffer
    call read_input_buffer     ; function does everything good, tested
    mov read_position, 0       ; nullify position
    mov ch, 0h                 ; ch=0
    mov cl, read_buffer_length ; putting cl for loop. this function is used in loop
    mov si, offset read_buffer ; putting beginning of buffer

  @@not_less:                  ; in this case we dont need extra reading to buffer, it has enough bytes
    mov al, [si]               ; i want result in al
    inc si                     ; increasing value of pointer
    inc read_position          ; increasing position number
  ret
endp

Answer 1

Simple enough!

jge @@not_less

This does not correspond to your comment! Use jle.