comedi_fc.c revision 0a85b6f0ab0d2edb0d41b32697111ce0e4f43496 
1/*
2    comedi/drivers/comedi_fc.c
3
4    This is a place for code driver writers wish to share between
5    two or more drivers.  fc is short
6    for frank-common.
7
8    Author:  Frank Mori Hess <fmhess@users.sourceforge.net>
9    Copyright (C) 2002 Frank Mori Hess
10
11    This program is free software; you can redistribute it and/or modify
12    it under the terms of the GNU General Public License as published by
13    the Free Software Foundation; either version 2 of the License, or
14    (at your option) any later version.
15
16    This program is distributed in the hope that it will be useful,
17    but WITHOUT ANY WARRANTY; without even the implied warranty of
18    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19    GNU General Public License for more details.
20
21    You should have received a copy of the GNU General Public License
22    along with this program; if not, write to the Free Software
23    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24
25************************************************************************/
26
27#include "../comedidev.h"
28
29#include "comedi_fc.h"
30
31static void increment_scan_progress(struct comedi_subdevice *subd,
32				    unsigned int num_bytes)
33{
34	struct comedi_async *async = subd->async;
35	unsigned int scan_length = cfc_bytes_per_scan(subd);
36
37	async->scan_progress += num_bytes;
38	if (async->scan_progress >= scan_length) {
39		async->scan_progress %= scan_length;
40		async->events |= COMEDI_CB_EOS;
41	}
42}
43
44/* Writes an array of data points to comedi's buffer */
45unsigned int cfc_write_array_to_buffer(struct comedi_subdevice *subd,
46				       void *data, unsigned int num_bytes)
47{
48	struct comedi_async *async = subd->async;
49	unsigned int retval;
50
51	if (num_bytes == 0)
52		return 0;
53
54	retval = comedi_buf_write_alloc(async, num_bytes);
55	if (retval != num_bytes) {
56		printk("comedi: buffer overrun\n");
57		async->events |= COMEDI_CB_OVERFLOW;
58		return 0;
59	}
60
61	comedi_buf_memcpy_to(async, 0, data, num_bytes);
62	comedi_buf_write_free(async, num_bytes);
63	increment_scan_progress(subd, num_bytes);
64	async->events |= COMEDI_CB_BLOCK;
65
66	return num_bytes;
67}
68
69EXPORT_SYMBOL(cfc_write_array_to_buffer);
70
71unsigned int cfc_read_array_from_buffer(struct comedi_subdevice *subd,
72					void *data, unsigned int num_bytes)
73{
74	struct comedi_async *async = subd->async;
75
76	if (num_bytes == 0)
77		return 0;
78
79	num_bytes = comedi_buf_read_alloc(async, num_bytes);
80	comedi_buf_memcpy_from(async, 0, data, num_bytes);
81	comedi_buf_read_free(async, num_bytes);
82	increment_scan_progress(subd, num_bytes);
83	async->events |= COMEDI_CB_BLOCK;
84
85	return num_bytes;
86}
87
88EXPORT_SYMBOL(cfc_read_array_from_buffer);
89
90unsigned int cfc_handle_events(struct comedi_device *dev,
91			       struct comedi_subdevice *subd)
92{
93	unsigned int events = subd->async->events;
94
95	if (events == 0)
96		return events;
97
98	if (events & (COMEDI_CB_EOA | COMEDI_CB_ERROR | COMEDI_CB_OVERFLOW))
99		subd->cancel(dev, subd);
100
101	comedi_event(dev, subd);
102
103	return events;
104}
105
106EXPORT_SYMBOL(cfc_handle_events);
107
108MODULE_AUTHOR("Frank Mori Hess <fmhess@users.sourceforge.net>");
109MODULE_DESCRIPTION("Shared functions for Comedi low-level drivers");
110MODULE_LICENSE("GPL");
111
112static int __init comedi_fc_init_module(void)
113{
114	return 0;
115}
116
117static void __exit comedi_fc_cleanup_module(void)
118{
119}
120
121module_init(comedi_fc_init_module);
122module_exit(comedi_fc_cleanup_module);
123