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;;; PolledSerial - simple serial I/O
;;;
;;; Copyright (c) 2009 Openmoko Inc.
;;;
;;; Authors Christopher Hall <hsw@openmoko.com>
;;;
;;; 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.
;;;
;;; THIS SOFTWARE IS PROVIDED BY THE 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 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.
.include "regs.inc"
;;; register usage
;;; r0 .. r3 must be preserved
;;; r4 result low
;;; r5 result high
;;; r6 .. r9 arguments 1..4
;;; r10 ..r14 reserved
;;; r15 __dp value
.section .text
;;; wait for serial output ready
;;; input:
;;; output:
;;; r4 = true if space in buffer, false if buffer is full
.global PolledSerial_PutReady
PolledSerial_PutReady:
xld.w %r4, R8_EFSIF0_STATUS
ld.ub %r5, [%r4]
and %r5, TDBEx
jreq PolledSerial_PutReady_done
ld.w %r4, 1
PolledSerial_PutReady_done:
ret
;;; print a character
;;; input:
;;; r6 = char
;;; output:
.global PolledSerial_PutChar
PolledSerial_PutChar:
xld.w %r4, R8_EFSIF0_STATUS
PolledSerial_PutChar_wait:
ld.ub %r5, [%r4]
and %r5, TDBEx
jreq PolledSerial_PutChar_wait
xld.w %r5, R8_EFSIF0_TXD
ld.b [%r5], %r6
ret
;;; read a character
;;; input:
;;; output:
;;; r4 = char
.global PolledSerial_GetChar
PolledSerial_GetChar:
call PolledSerial_InputAvailable
or %r4, %r4
jreq PolledSerial_GetChar
xld.w %r4, R8_EFSIF0_RXD
ld.ub %r4, [%r4]
ret
;;; see if input is available
;;; input:
;;; output:
;;; r4 = 0 => not ready
;;; 1 => ready
.global PolledSerial_InputAvailable
PolledSerial_InputAvailable:
xld.w %r4, R8_EFSIF0_STATUS
ld.ub %r4, [%r4]
and %r4, RDBFx
jreq PolledSerial_InputAvailable_done
ld.w %r4, 1
PolledSerial_InputAvailable_done:
ret
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