125 lines
3.3 KiB
C
125 lines
3.3 KiB
C
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/*
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* uart.c
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*
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* Copyright (c) 2005 Robert Krten. All Rights Reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* This module contains a simple 8-bit UART, which performs a callback
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* with the decoded byte value.
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*
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* 2005 06 11 R. Krten created
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include "uart.h"
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/*
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* dsp_uart_attr_init
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*
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* Initializes the attributes structure; this must be done before the
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* attributes structure is used.
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*/
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void dsp_uart_attr_init (dsp_uart_attr_t *attr)
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{
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memset (attr, 0, sizeof (*attr));
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}
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/*
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* dsp_uart_attr_get_bytehandler
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* dsp_uart_attr_set_bytehandler
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*
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* These functions get and set their respective elements from the
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* attributes structure. If an error code is returned, it is just
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* zero == ok, -1 == fail.
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*/
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bytehandler_func_t dsp_uart_attr_get_bytehandler(dsp_uart_attr_t *attr, void **bytehandler_arg)
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{
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*bytehandler_arg = attr->bytehandler_arg;
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return attr->bytehandler;
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}
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void dsp_uart_attr_set_bytehandler(dsp_uart_attr_t *attr, bytehandler_func_t bytehandler, void *bytehandler_arg)
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{
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attr->bytehandler = bytehandler;
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attr->bytehandler_arg = bytehandler_arg;
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}
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dsp_uart_handle_t *dsp_uart_create(dsp_uart_attr_t *attr)
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{
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dsp_uart_handle_t *handle;
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handle = malloc(sizeof (*handle));
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if (handle) {
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memset(handle, 0, sizeof (handle));
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/* fill the attributes member */
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memcpy(&handle->attr, attr, sizeof (*attr));
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}
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return handle;
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}
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void dsp_uart_destroy(dsp_uart_handle_t **handle)
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{
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if (*handle) {
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free(*handle);
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*handle = NULL;
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}
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}
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void dsp_uart_bit_handler(void *x, int bit)
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{
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dsp_uart_handle_t *handle = (dsp_uart_handle_t *) x;
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if (!handle->have_start) {
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if (bit) {
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return; /* waiting for start bit (0) */
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}
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handle->have_start = 1;
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handle->data = 0;
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handle->nbits = 0;
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return;
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}
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handle->data >>= 1;
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handle->data |= 0x80 * !!bit;
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handle->nbits++;
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if (handle->nbits == 8) {
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handle->attr.bytehandler(handle->attr.bytehandler_arg, handle->data);
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handle->nbits = 0;
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handle->data = 0;
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handle->have_start = 0;
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}
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/* might consider handling errors in the future... */
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}
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