aisetfreq.c
3.31 KB
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
/*====================================================================
* aisetfreq.c
*
* Copyright 1995, Silicon Graphics, Inc.
* All Rights Reserved.
*
* This is UNPUBLISHED PROPRIETARY SOURCE CODE of Silicon Graphics,
* Inc.; the contents of this file may not be disclosed to third
* parties, copied or duplicated in any form, in whole or in part,
* without the prior written permission of Silicon Graphics, Inc.
*
* RESTRICTED RIGHTS LEGEND:
* Use, duplication or disclosure by the Government is subject to
* restrictions as set forth in subdivision (c)(1)(ii) of the Rights
* in Technical Data and Computer Software clause at DFARS
* 252.227-7013, and/or in similar or successor clauses in the FAR,
* DOD or NASA FAR Supplement. Unpublished - rights reserved under the
* Copyright Laws of the United States.
*====================================================================*/
/**************************************************************************
*
* $Revision: 1.1.1.2 $
* $Date: 2002/10/29 08:06:43 $
* $Source: /root/leakn64/depot/rf/sw/n64os20l/libultra/monegi/ai/aisetfreq.c,v $
*
**************************************************************************/
#include "osint.h"
#include "rcp.h"
#include "assert.h"
extern int osViClock;
/*
* Name: osAiSetFrequency
*
* Description:
* Based on the input frequency, calculate the corresponding values for
* the two internal divisors.
*
* Upon completion, return the nearest frequency that the divisors can
* generate. If the requested frequency is not within allowable range,
* return a "-1".
*
* Globals Referenced:
* osViClock (vi.c) - video clock frequency in Hz (either
* VI_NTSC_CLOCK or VI_PAL_CLOCK)
*/
s32
osAiSetFrequency(u32 frequency)
{
register unsigned int dacRate;
register unsigned char bitRate;
register float f;
/* Based on frequency, find the corresponding values for DAC rate and
* BIT rate registers. Also, return the closest frequency to caller.
*/
#ifdef _DEBUG
/* Check for valid AI frequency range based on video clock */
if (osViClock == VI_PAL_CLOCK) {
if ((frequency < AI_PAL_MIN_FREQ) || (frequency > AI_PAL_MAX_FREQ)) {
__osError(ERR_OSAISETFREQUENCY, 3,
AI_PAL_MIN_FREQ, AI_PAL_MAX_FREQ, frequency);
return(-1);
}
}
else if (osViClock == VI_MPAL_CLOCK) {
if ((frequency < AI_MPAL_MIN_FREQ) || (frequency > AI_MPAL_MAX_FREQ)) {
__osError(ERR_OSAISETFREQUENCY, 3,
AI_MPAL_MIN_FREQ, AI_MPAL_MAX_FREQ, frequency);
return(-1);
}
}
else { /* Assume that it's NTSC */
if ((frequency < AI_NTSC_MIN_FREQ) || (frequency > AI_NTSC_MAX_FREQ)) {
__osError(ERR_OSAISETFREQUENCY, 3,
AI_NTSC_MIN_FREQ, AI_NTSC_MAX_FREQ, frequency);
return(-1);
}
}
#endif
f = ((float)osViClock / (float)frequency) + 0.5F; /* Rounding up */
dacRate = (unsigned int)f;
if (dacRate < AI_MIN_DAC_RATE)
return(-1);
/* if bitRate is 0, abus clock stops */
bitRate = (unsigned char)(dacRate / 66);
if (bitRate > AI_MAX_BIT_RATE)
bitRate = AI_MAX_BIT_RATE;
IO_WRITE(AI_DACRATE_REG, dacRate-1);
IO_WRITE(AI_BITRATE_REG, bitRate-1);
/* Return the closest frequency */
return((s32)((s32)osViClock/(s32)dacRate));
} /* osAiSetFrequency */