84 lines
3.7 KiB
C
84 lines
3.7 KiB
C
/* Line printer stuff mostly follows the original Centronics printers. See
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IEEE Std.1284-1994 Standard Signaling Method for a Bi-directional Parallel
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Peripheral Interface for Personal Computers for 5 modes of data transfer. */
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/* Parallel port registers: data (0x3bc, 0x378, 0x278), status=data+1, control=data+2 */
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/* Parallel port status register (read only):
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bit 7: NBSY (1: ready, 0: busy or error or off-line)
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bit 6: NACK (if NBSY=1, then 1; if NBSY=0 then 1: sending data, 0: ready with data)
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bit 5: PAP (1: out-of-paper)
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bit 4: OFON (1: on-line)
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bit 3: NFEH (1: OK, 0: printer error)
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bits 2-0: 07
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On out-of-paper: PAP=1, OFON=0, NFEH=1.
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"When reading the busy status, read twice in a row and use the value
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obtained from the second read. This improves the reliability on some
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parallel ports when the busy line may not be connected and is floating."
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"On some Okidata printers when the busy signal switches from high to low,
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the printer sends a 50 ns glitch on the paper out signal line. Before
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declaring a paper out condition, check the status again."
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(The Undocumented PC, F. van Gilluwe, p. 711)
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*/
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/* Parallel port control register (read/write):
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bit 4: IRQ (1: we want an interrupt when NACK goes from 1 to 0)
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bit 3: DSL (1: activate printer)
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bit 2: NINI (0: initialise printer)
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bit 1: ALF (1: printer performs automatic linefeed after each line)
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bit 0: STR (0->1: generate a Strobe pulse: transport data to printer)
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*/
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/* Parallel port timing:
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1. wait for NBSY=1
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2. outb(data byte, data port)
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3. wait for at least 0.5us
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4. read control port, OR with STR=0x1, output to control port - purpose:
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generate strobe pulse; this will make the busy line go high
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5. wait for at least 0.5us
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6. read control port, AND with !STR, output to control port
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7. wait for at least 0.5us
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8. in a loop: read status register until NACK bit is 0 or NBSY=1
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(the printer will keep NACK=0 for at least 0.5us, then NACK=NBSY=1).
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*/
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/* lp ioctls */
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#define LPCHAR 0x0601 /* specify the number of times we ask for the status
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(waiting for ready) before giving up with a timeout
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The duration may mainly depend on the timing of an inb. */
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#define LPTIME 0x0602 /* time to sleep after each timeout (in units of 0.01 sec) */
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#define LPABORT 0x0604 /* call with TRUE arg to abort on error,
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FALSE to retry. Default is retry. */
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#define LPSETIRQ 0x0605 /* call with new IRQ number,
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or 0 for polling (no IRQ) */
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#define LPGETIRQ 0x0606 /* get the current IRQ number */
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#define LPWAIT 0x0608 /* #of loops to wait before taking strobe high */
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#define LPCAREFUL 0x0609 /* call with TRUE arg to require out-of-paper, off-
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line, and error indicators good on all writes,
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FALSE to ignore them. Default is ignore. */
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#define LPABORTOPEN 0x060a /* call with TRUE arg to abort open() on error,
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FALSE to ignore error. Default is ignore. */
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#define LPGETSTATUS 0x060b /* return LP_S(minor) */
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#define LPRESET 0x060c /* reset printer */
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#define LPGETFLAGS 0x060e /* get status flags */
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#define LPSTRICT 0x060f /* enable/disable strict compliance (2.0.36) */
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/* Strict: wait until !READY before taking strobe low;
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this may be bad for the Epson Stylus 800.
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Not strict: wait a constant time as given by LPWAIT */
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#define LPTRUSTIRQ 0x060f /* set/unset the LP_TRUST_IRQ flag (2.1.131) */
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/*
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* bit defines for 8255 status port
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* base + 1
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* accessed with LP_S(minor), which gets the byte...
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*/
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#define LP_PBUSY 0x80 /* inverted input, active high */
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#define LP_PACK 0x40 /* unchanged input, active low */
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#define LP_POUTPA 0x20 /* unchanged input, active high */
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#define LP_PSELECD 0x10 /* unchanged input, active high */
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#define LP_PERRORP 0x08 /* unchanged input, active low */
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