mirror of
https://github.com/rzzzwilson/pymlac.git
synced 2025-06-10 09:32:41 +00:00
137 lines
3.5 KiB
C
137 lines
3.5 KiB
C
/*
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* Implementation for the imlac TTYOUT (TTY output) device.
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*/
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#include "imlac.h"
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#include "ttyout.h"
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/*****
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* constants for the TTYOUT device
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*
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* The device reads at 4800 chars/second, so we work out how many imlac
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* machine cycles data is ready/notready at a 30%/70% ready cycle.
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******/
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#define CHARS_PER_SECOND 4800
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#define CYCLES_PER_CHAR (CPU_HERZ / CHARS_PER_SECOND)
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#define READY_CYCLES (int)((3 * CYCLES_PER_CHAR) / 10)
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#define NOT_READY_CYCLES (int)((7 * CYCLES_PER_CHAR) / 10)
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#define TTYOUT_EOF 0377
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/*****
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* State variables for the TTYOUT device
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******/
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static bool device_ready = false;
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static FILE *open_file;
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static char *filename = NULL;
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static long cycle_count = 0;
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/******************************************************************************
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Description : Mount a papertape file on the TTYOUT device
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Parameters : fname - pathname of the file to mount
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Returns : 0 if no error, else status code.
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Comments :
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******************************************************************************/
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int ttyout_mount(char *fname)
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{
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filename = fname;
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open_file = fopen(fname, "wb");
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if (open_file == NULL)
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{
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ttyout_dismount();
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return errno;
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}
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device_ready = false;
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cycle_count = NOT_READY_CYCLES;
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return 0;
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}
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/******************************************************************************
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Description : Dismount papertape file from device.
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Parameters :
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Returns :
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Comments : Turns motor off.
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******************************************************************************/
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void ttyout_dismount(void)
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{
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if (open_file)
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if (fclose(open_file) != 0)
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filename = NULL;
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open_file = NULL;
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device_ready = true;
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}
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/******************************************************************************
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Description : Write a byte value to the device.
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Parameters :
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Returns :
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Comments :
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******************************************************************************/
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void ttyout_send(BYTE value)
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{
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if (device_ready)
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fwrite(&value, 1, 1, open_file);
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}
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/******************************************************************************
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Description : Get the papertape device status.
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Parameters :
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Returns : TRUE if device ready, else FALSE.
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Comments :
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******************************************************************************/
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void ttyout_clear_flag(void)
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{
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device_ready = false;
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}
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/******************************************************************************
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Description : Get the papertape device status.
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Parameters :
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Returns : TRUE if device ready, else FALSE.
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Comments :
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******************************************************************************/
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bool ttyout_ready(void)
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{
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return device_ready;
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}
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/******************************************************************************
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Description : Tick the state machine along a bit.
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Parameters : cycles - number of imlac cycles that have elapsed
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Returns :
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Comments :
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******************************************************************************/
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void ttyout_tick(long cycles)
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{
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/* if not open, no state change */
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if (open_file == NULL)
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return;
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/* file mounted */
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cycle_count -= cycles;
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if (cycle_count <= 0L)
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{
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if (device_ready)
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{
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device_ready = false;
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cycle_count += NOT_READY_CYCLES;
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}
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else
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{
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device_ready = true;
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cycle_count += READY_CYCLES;
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}
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}
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}
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