; ***************************************************************************
; copyright   : (C) 2025 by Martin Preuss
; email       : martin@libchipcard.de
;
; ***************************************************************************
; * This file is part of the project "AqHome".                              *
; * Please see toplevel file COPYING of that project for license details.   *
; ***************************************************************************


.dseg

uartHwDataBegin:
  ; fixed buffers for incoming and outgoing messages
  uartHw_buffers:             .byte UART_HW_FIXEDBUFFERS_NUM*UART_HW_FIXEDBUFFERS_SIZE
uartHwDataEnd:



.cseg



; ---------------------------------------------------------------------------
; @routine UART_HW_FixedBuffers_Init @global
;
; @clobbers R16, R17, X

UART_HW_FixedBuffers_Init:
  ldi xl, LOW(uartHw_buffers)
  ldi xh, HIGH(uartHw_buffers)
  m_fixedbuf_init UART_HW_FIXEDBUFFERS_SIZE, UART_HW_FIXEDBUFFERS_NUM
  ret
; @end



; ---------------------------------------------------------------------------
; @routine UART_HW_FixedBuffers_Alloc @global
;
; @return CFLAG set if buffer available, cleared otherwise
; @return r16 buffer num
; @return X pointer to start of buffer
; @clobbers R16, R17, X

UART_HW_FixedBuffers_Alloc:
  ldi xl, LOW(uartHw_buffers)
  ldi xh, HIGH(uartHw_buffers)
  m_fixedbuf_reserve UART_HW_FIXEDBUFFERS_SIZE, UART_HW_FIXEDBUFFERS_NUM
  ret
; @end



; ---------------------------------------------------------------------------
; @routine UART_HW_FixedBuffers_Release @global
;
; @param X pointer to start of buffers
; @clobbers R16

UART_HW_FixedBuffers_Release:
  m_fixedbuf_release
  ret
; @end



; ---------------------------------------------------------------------------
; @routine UART_HW_FixedBuffers_Locate
;
; Get position of a given buffer.
;
; CAVE: need to change this routine if UART_HW_FIXEDBUFFERS_SIZE is changed!
;
; @return CFLAG set if okay, cleared on error
; @return X points to start of buffer with the given num
; @param r16 buffer num (0-max)
; @clobbers r16

UART_HW_FixedBuffers_Locate:
  cpi r16, UART_HW_FIXEDBUFFERS_NUM
  brcc UART_HW_FixedBuffers_Locate_end ; out of range
  mov xh, r16  ; * 256
  clr xl
  lsr xh       ; *128
  ror xl
  lsr xh       ; *64
  ror xl
  lsr xh       ; *32
  ror xl
  ldi r16, LOW(uartHw_buffers)
  add xl, r16
  ldi r16, HIGH(uartHw_buffers)
  adc xh, r16
  sec
UART_HW_FixedBuffers_Locate_end:
  ret
; @end