Subversion Repositories ssbcc

; Copyright 2015, Sinclair R.F., Inc.

; demonstrate dual interrupt peripheral

.memory ROM myrom

.variable msg N"INT\n"

.memory RAM myram

.variable ixMsg 0

.main

  ; Mask all but the external interrupt and then enable interrupts.

  C_INTERRUPT .outport(O_INTERRUPT_MASK)

  .ena

  ; Sit in an infinite loop while the interrupt handler does everything else.

  :infinite .jump(infinite)

.interrupt

  ; Get the interrupt event(s).

  ; ( - u_int )

  .inport(I_INTERRUPT)

  ; Test for the external interrupt.

  ; ( u_int - u_int )

  dup C_INTERRUPT & 0= .jumpc(not_external)

    ; Set the index into the output message.

    msg .storevalue(ixMsg)

    ; Enable the UART_Tx interrupt.

    .inport(I_INTERRUPT_MASK) C_UART_TX_INTERRUPT or .outport(O_INTERRUPT_MASK)

  :not_external

  ; Test for the UART_Tx not_busy interrupt.

  ; ( u_int - u_int )

  dup C_UART_TX_INTERRUPT & 0= .jumpc(not_uart)

    ; Get the next character to transmit and move the pointer to the next

    ; character.

    ; ( - u_char )

    .fetchvalue(ixMsg) .fetch+(myrom) .storevalue(ixMsg)

    ; If the character is a terminating null character then discard it and

    ; disable this part of the interrupt, otherwise output it.

    .jumpc(not_null,nop)

      ; ( u_char - )

      drop

      .inport(I_INTERRUPT_MASK) ${~C_UART_TX_INTERRUPT} & .outport(O_INTERRUPT_MASK)

      .jump(not_uart)

    :not_null

      ; ( u_char - )

      .outport(O_UART_TX)

  :not_uart

  ; Drop the interrupt event from the data stack and return from the interrupt.

  ; ( u_int - )

  drop .returni