;**************************************************************************
; arch/z80/src/ze80/ez80_io.c
;
; Copyright (C) 2008-2009 Gregory Nutt. All rights reserved.
; Author: Gregory Nutt <gnutt@nuttx.org>
;
; Redistribution and use in source and binary forms, with or without
; modification, are permitted provided that the following conditions
; are met:
;
; 1. Redistributions of source code must retain the above copyright
; notice, this list of conditions and the following disclaimer.
; 2. Redistributions in binary form must reproduce the above copyright
; notice, this list of conditions and the following disclaimer in
; the documentation and/or other materials provided with the
; distribution.
; 3. Neither the name NuttX nor the names of its contributors may be
; used to endorse or promote products derived from this software
; without specific prior written permission.
;
; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
; FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
; COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
; INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
; BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
; OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
; AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
; LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
; ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
; POSSIBILITY OF SUCH DAMAGE.
;
;**************************************************************************
;**************************************************************************
; Global Symbols Imported
;**************************************************************************
;**************************************************************************
; Global Symbols Expported
;**************************************************************************
xdef _outp
xdef _inp
;**************************************************************************
; Global Symbols Expported
;**************************************************************************
CONFIG_EZ80_Z80MODE equ 0
;**************************************************************************
; Code
;**************************************************************************
segment CODE
.assume ADL=1
;**************************************************************************
; Name: void outp(uint16_t p, uint8_t c)
;
; Description:
; Output byte c on port p
;
;**************************************************************************
_outp:
; Create a stack frame
push ix
ld ix, #0
add ix, sp
; Get the arguments from the stack
.if CONFIG_EZ80_Z80MODE
; Stack looks like:
;
; 7-8 Unused
; 6 Value
; 4-5 Port
; 2-3 Return address
; SP: 0-1 Caller's fame pointer
ld bc, (ix + 4) ; Port
ld a, (ix + 6) ; Value
.else
; Stack looks like:
;
; 10-11 Unused
; 9 Value
; 8 Unused
; 6-7 Port
; 3-5 Return address
; SP: 0-2 Caller's frame pointer
ld bc, (ix + 6) ; Port (upper 8 bits not used)
ld a, (ix + 9) ; Value
.endif
; Output the specified by to the specified 8-bit I/O address
out (bc), a
pop ix
ret
;**************************************************************************
; Name: uint8_t inp(uint16_t p)
;
; Description:
; Input byte from port p
;
;**************************************************************************
_inp:
; Create a stack frame
push ix
ld ix, #0
add ix, sp
; Get the arguments from the stack
.if CONFIG_EZ80_Z80MODE
; Stack looks like:
;
; 4-5 Port
; 2-3 Return address
; SP: 0-1 Caller's fame pointer
ld bc, (ix + 4) ; Port
.else
; Stack looks like:
;
; 8 Unused
; 6-7 Port
; 3-5 Return address
; SP: 0-2 Caller's frame pointer
ld bc, (ix + 6) ; Port (upper 8 bits not used)
.endif
; Return port value in A
in a, (bc)
pop ix
ret
end
