OpenCores
URL https://opencores.org/ocsvn/forwardcom/forwardcom/trunk

Subversion Repositories forwardcom

[/] [forwardcom/] [libraries/] [getch_light.as] - Blame information for rev 168

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 88 Agner
/*********************************  getch_light.as ****************************
2
* Author:        Agner Fog
3
* date created:  2021-05-25
4
* Last modified: 2021-05-25
5
* Version:       1.11
6
* Project:       ForwardCom library libc_light.li
7
* Description:   Common C functions: _kbhit, getch, getche
8
*                Nonstandard function: getch_nonblocking
9
*
10
* This version is for small CPUs with limited capabilities
11
* The following instructions are avoided: mul, div, push, pop, sys_call.
12
* Input comes directly from input port 8
13
* Output to stdout goes directly to output port 10
14
*
15
* The functions _kbhit, getch, getche are common, but not part of the official C standard.
16
* getch_nonblocking is my own invention. It is sadly missing in common systems
17
*
18
* C declarations:
19
* int _kbhit(void);
20
* int getch(void);
21
* int getche(void);
22
* int getch_nonblocking(void);
23
*
24
* Description:
25
* _kbhit:   return 1 if there is at least one character in the input buffer, 0 if buffer empty
26
* getch:    waits for input from stdin. returns one character
27
* getche:   same as getch. The input is echoed to the standard output
28
* getch_nonblocking: reads one character from stdin without waiting. returns -1 if the input buffer is empty
29
*
30
* Copyright 2021 GNU General Public License http://www.gnu.org/licenses
31
*****************************************************************************/
32
 
33
// define input and output ports
34
%stdin_port = 8
35
%stdin_status_port = 9
36
%stdout_port = 10
37
 
38
 
39
code section execute
40
 
41
// _kbhit function
42
// returns 0 if there is no input
43
// returns 1 if the standard input input buffer contains at least one character
44
_kbhit function public reguse = 1,0
45
__kbhit function public reguse = 1,0
46
 
47
  int r0 = input(r0, stdin_status_port)// read status port
48
  int16 r0 = r0 != 0                   // bit 0-15 = number of bytes in input buffer
49
  return
50
 
51
 
52
// _getch function
53
// waits for input from standard input. returns one character in the interval 0 - 0xFF
54
// no error checking
55
_getch function public reguse = 1,0
56
 
57
  do {                                 // keep reading until input data valid
58
    int r0 = input(r0, stdin_port)     // read from input port
59
  }
60
  while (int !(r0 & 0x100));           // bit 8 = data valid
61
  int8 r0 = r0                         // isolate bit 0-7
62
  return
63
 
64
 
65
// _getche function
66
// same as _getch
67
// echoes character to standard output
68
_getche function public reguse = 1,0
69
 
70
  do {                                 // keep reading until input data valid
71
    int r0 = input(r0, stdin_port)     // read from input port
72
  }
73
  while (int !(r0 & 0x100));           // bit 8 = data valid
74
  int8 r0 = r0                         // isolate bit 0-7
75
  int output(r0, r0, stdout_port)      // output the same character
76
  return
77
 
78
 
79
// _getch_nonblocking function
80
// reads input from standard input. Does not wait for input
81
// returns one character in the interval 0 - 0xFF if input available
82
// returns -1 if input buffer empty
83
// future implementations may return other negative values in case of error
84
_getch_nonblocking function public reguse = 1,0
85
 
86
  int r0 = input(r0, stdin_port)       // read from input port
87
  if (int (r0 & 0x100)) {              // bit 8 = data valid
88
    int8 r0 = r0                       // isolate bit 0-7
89
    return
90
  }
91
  int r0 = -1                          // input buffer empty. return -1
92
  return
93
 
94
code end

powered by: WebSVN 2.1.0

© copyright 1999-2024 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.