aboutsummaryrefslogtreecommitdiffstats
path: root/examples/baremetal/cy7c68013a/nes-gamepads/core.c
blob: 17a9661ebde5f2a37642ea1518c32bac7cf1b071 (plain)
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
/****************************************************************************
**
** Copyright (C) 2019 Denis Shienkov <denis.shienkov@gmail.com>
** Contact: https://www.qt.io/licensing/
**
** This file is part of the examples of Qbs.
**
** $QT_BEGIN_LICENSE:BSD$
** Commercial License Usage
** Licensees holding valid commercial Qt licenses may use this file in
** accordance with the commercial license agreement provided with the
** Software or, alternatively, in accordance with the terms contained in
** a written agreement between you and The Qt Company. For licensing terms
** and conditions see https://www.qt.io/terms-conditions. For further
** information use the contact form at https://www.qt.io/contact-us.
**
** BSD License Usage
** Alternatively, you may use this file under the terms of the BSD license
** as follows:
**
** "Redistribution and use in source and binary forms, with or without
** modification, are permitted provided that the following conditions are
** met:
**   * Redistributions of source code must retain the above copyright
**     notice, this list of conditions and the following disclaimer.
**   * 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.
**   * Neither the name of The Qt Company Ltd 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."
**
** $QT_END_LICENSE$
**
****************************************************************************/

#include "core.h"
#include "regs.h"

enum cpu_freq_clk {
    CPU_CLK_12M = 0,
    CPU_CLK_24M,
    CPU_CLK_48M
};

#define cpu_freq_clk_get() \
    ((CPUCS & bmCLKSPD) >> 3)

#define cpu_freq_clk_set(freq_clk) \
    CPUCS = (CPUCS & ~bmCLKSPD) | (freq_clk << 3)

void core_init(void)
{
    // Set CPU clock to 48MHz.
    cpu_freq_clk_set(CPU_CLK_48M);
    sync_delay();
    // Set stretch to 0.
    CKCON = ((CKCON & (~bmSTRETCH)) | bmFW_STRETCH1);
    sync_delay();
    // Clear breakpoint register.
    BREAKPT = 0;
    sync_delay();
    // Set all 8051 interrupts to low priority
    IP = 0;
    sync_delay();
    // Clear interrupt enable bits.
    EIE = 0;
    sync_delay();
    // Clear all external interrupt flags.
    EXIF = 0;
    sync_delay();
}