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[/] [forwardcom/] [libraries/] [getch_light.as] - Blame information for rev 120

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1 88 Agner
/*********************************  getch_light.as ****************************
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* Author:        Agner Fog
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* date created:  2021-05-25
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* Last modified: 2021-05-25
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* Version:       1.11
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* Project:       ForwardCom library libc_light.li
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* Description:   Common C functions: _kbhit, getch, getche
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*                Nonstandard function: getch_nonblocking
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*
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* This version is for small CPUs with limited capabilities
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* The following instructions are avoided: mul, div, push, pop, sys_call.
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* Input comes directly from input port 8
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* Output to stdout goes directly to output port 10
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*
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* The functions _kbhit, getch, getche are common, but not part of the official C standard.
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* getch_nonblocking is my own invention. It is sadly missing in common systems
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*
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* C declarations:
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* int _kbhit(void);
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* int getch(void);
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* int getche(void);
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* int getch_nonblocking(void);
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*
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* Description:
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* _kbhit:   return 1 if there is at least one character in the input buffer, 0 if buffer empty
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* getch:    waits for input from stdin. returns one character
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* getche:   same as getch. The input is echoed to the standard output
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* getch_nonblocking: reads one character from stdin without waiting. returns -1 if the input buffer is empty
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*
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* Copyright 2021 GNU General Public License http://www.gnu.org/licenses
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*****************************************************************************/
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// define input and output ports
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%stdin_port = 8
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%stdin_status_port = 9
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%stdout_port = 10
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code section execute
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// _kbhit function
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// returns 0 if there is no input
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// returns 1 if the standard input input buffer contains at least one character
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_kbhit function public reguse = 1,0
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__kbhit function public reguse = 1,0
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  int r0 = input(r0, stdin_status_port)// read status port
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  int16 r0 = r0 != 0                   // bit 0-15 = number of bytes in input buffer
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  return
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// _getch function
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// waits for input from standard input. returns one character in the interval 0 - 0xFF
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// no error checking
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_getch function public reguse = 1,0
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  do {                                 // keep reading until input data valid
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    int r0 = input(r0, stdin_port)     // read from input port
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  }
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  while (int !(r0 & 0x100));           // bit 8 = data valid
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  int8 r0 = r0                         // isolate bit 0-7
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  return
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// _getche function
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// same as _getch
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// echoes character to standard output
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_getche function public reguse = 1,0
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  do {                                 // keep reading until input data valid
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    int r0 = input(r0, stdin_port)     // read from input port
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  }
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  while (int !(r0 & 0x100));           // bit 8 = data valid
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  int8 r0 = r0                         // isolate bit 0-7
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  int output(r0, r0, stdout_port)      // output the same character
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  return
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// _getch_nonblocking function
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// reads input from standard input. Does not wait for input
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// returns one character in the interval 0 - 0xFF if input available
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// returns -1 if input buffer empty
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// future implementations may return other negative values in case of error
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_getch_nonblocking function public reguse = 1,0
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  int r0 = input(r0, stdin_port)       // read from input port
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  if (int (r0 & 0x100)) {              // bit 8 = data valid
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    int8 r0 = r0                       // isolate bit 0-7
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    return
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  }
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  int r0 = -1                          // input buffer empty. return -1
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  return
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