sdcc/device/lib/ser_ir.c

   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 }