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  1. /*-------------------------------------------------------------------------
  2.    ser_ir.h - source file for serial routines
  3.  
  4.    Copyright (C) 1999, Josef Wolf <jw AT raven.inka.de>
  5.  
  6.    This library is free software; you can redistribute it and/or modify it
  7.    under the terms of the GNU General Public License as published by the
  8.    Free Software Foundation; either version 2, or (at your option) any
  9.    later version.
  10.  
  11.    This library is distributed in the hope that it will be useful,
  12.    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13.    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
  14.    GNU General Public License for more details.
  15.  
  16.    You should have received a copy of the GNU General Public License
  17.    along with this library; see the file COPYING. If not, write to the
  18.    Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
  19.    MA 02110-1301, USA.
  20.  
  21.    As a special exception, if you link this library with other files,
  22.    some of which are compiled with SDCC, to produce an executable,
  23.    this library does not by itself cause the resulting executable to
  24.    be covered by the GNU General Public License. This exception does
  25.    not however invalidate any other reasons why the executable file
  26.    might be covered by the GNU General Public License.
  27. -------------------------------------------------------------------------*/
  28.  
  29. #include "ser_ir.h"
  30.  
  31. /* This file implements a serial interrupt handler and its supporting
  32. * routines. Compared with the existing serial.c and _ser.c it has
  33. * following advantages:
  34. * - You can specify arbitrary buffer sizes (umm, up to 255 bytes),
  35. *   so it can run on devices with _little_ memory like at89cx051.
  36. * - It won't overwrite characters which already are stored in the
  37. *   receive-/transmit-buffer.
  38. */
  39.  
  40. /* BUG: those definitions (and the #include) should be set dynamically
  41. * (while linking or at runtime) to make this file a _real_ library.
  42. */
  43. #include <8051.h>
  44. #define XBUFLEN 4
  45. #define RBUFLEN 8
  46.  
  47. /* You might want to specify idata, pdata or xdata for the buffers */
  48. static unsigned char __pdata rbuf[RBUFLEN], xbuf[XBUFLEN];
  49. static unsigned char rcnt, xcnt, rpos, xpos;
  50. static __bit busy;
  51.  
  52. void
  53. ser_init (void)
  54. {
  55.    ES = 0;
  56.    rcnt = xcnt = rpos = xpos = 0;  /* init buffers */
  57.    busy = 0;
  58.    SCON = 0x50;
  59.    PCON |= 0x80;                   /* SMOD = 1; */
  60.    TMOD &= 0x0f;                   /* use timer 1 */
  61.    TMOD |= 0x20;
  62.    TL1 = -3; TH1 = -3; TR1 = 1;    /* 19200bps with 11.059MHz crystal */
  63.    ES = 1;
  64. }
  65.  
  66. void
  67. ser_handler (void) __interrupt 4
  68. {
  69.    if (RI) {
  70.            RI = 0;
  71.            /* don't overwrite chars already in buffer */
  72.            if (rcnt < RBUFLEN)
  73.                    rbuf [(unsigned char)(rpos+rcnt++) % RBUFLEN] = SBUF;
  74.    }
  75.    if (TI) {
  76.            TI = 0;
  77.            if (busy = xcnt) {   /* Assignment, _not_ comparison! */
  78.                    xcnt--;
  79.                    SBUF = xbuf [xpos++];
  80.                    if (xpos >= XBUFLEN)
  81.                            xpos = 0;
  82.            }
  83.    }
  84. }
  85.  
  86. void
  87. ser_putc (unsigned char c)
  88. {
  89.    while (xcnt >= XBUFLEN) /* wait for room in buffer */
  90.            ;
  91.    ES = 0;
  92.    if (busy) {
  93.            xbuf[(unsigned char)(xpos+xcnt++) % XBUFLEN] = c;
  94.    } else {
  95.            SBUF = c;
  96.            busy = 1;
  97.    }
  98.    ES = 1;
  99. }
  100.  
  101. unsigned char
  102. ser_getc (void)
  103. {
  104.    unsigned char c;
  105.    while (!rcnt)   /* wait for character */
  106.            ;
  107.    ES = 0;
  108.    rcnt--;
  109.    c = rbuf [rpos++];
  110.    if (rpos >= RBUFLEN)
  111.            rpos = 0;
  112.    ES = 1;
  113.    return (c);
  114. }
  115.  
  116. #pragma save
  117. #pragma noinduction
  118. void
  119. ser_puts (unsigned char *s)
  120. {
  121.    unsigned char c;
  122.    while (c=*s++) {
  123.            if (c == '\n') ser_putc ('\r');
  124.            ser_putc (c);
  125.    }
  126. }
  127. #pragma restore
  128.  
  129. void
  130. ser_gets (unsigned char *s, unsigned char len)
  131. {
  132.    unsigned char pos, c;
  133.  
  134.    pos = 0;
  135.    while (pos <= len) {
  136.            c = ser_getc ();
  137.            if (c == '\r') continue;        /* discard CR's */
  138.            s[pos++] = c;
  139.            if (c == '\n') break;           /* NL terminates */
  140.    }
  141.    s[pos] = '\0';
  142. }
  143.  
  144. unsigned char
  145. ser_can_xmt (void)
  146. {
  147.    return XBUFLEN - xcnt;
  148. }
  149.  
  150. unsigned char
  151. ser_can_rcv (void)
  152. {
  153.    return rcnt;
  154. }
  155.