sdcc-3.9.0 fork implementing GNU assembler syntax

This fork aims to provide better support for stm8-binutils

1 files changed, 101 insertions, 0 deletions

diff --git a/device/lib/_autobaud.c b/device/lib/_autobaud.c
new file mode 100644
index 0000000..73a4379
--- /dev/null
+++ b/device/lib/_autobaud.c
@@ -0,0 +1,101 @@
+/*-------------------------------------------------------------------------
+
+   _autobaud.c - automatic baud rate detection routine. Adapted for
+   sdcc compiler from Paul Stoffregen's  <paul@ece.orst.edu> autobaud.asm
+   the original assembly code can be found at 
+   http://www.ece.orst.edu/~paul/8051-goodies/autobaud.html  
+  
+   Copyright (C) 1999, Sandeep Dutta . sandeep.dutta@usa.net
+
+   This library is free software; you can redistribute it and/or modify it
+   under the terms of the GNU General Public License as published by the
+   Free Software Foundation; either version 2, or (at your option) any
+   later version.
+
+   This library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License 
+   along with this library; see the file COPYING. If not, write to the
+   Free Software Foundation, 51 Franklin Street, Fifth Floor, Boston,
+   MA 02110-1301, USA.
+
+   As a special exception, if you link this library with other files,
+   some of which are compiled with SDCC, to produce an executable,
+   this library does not by itself cause the resulting executable to
+   be covered by the GNU General Public License. This exception does
+   not however invalidate any other reasons why the executable file
+   might be covered by the GNU General Public License.
+-------------------------------------------------------------------------*/
+
+#include <8051.h>
+/*
+; To set the baud rate, use this formula or use autobaud()
+; baud_const = 256 - (crystal / (12 * 16 * baud)) */
+
+/*
+;to do automatic baud rate detection, we assume the user will
+;press the carriage return, which will cause this bit pattern
+;to appear on port 3 pin 0 (CR = ascii code 13, assume 8N1 format)
+;
+;              0 1 0 1 1 0 0 0 0 1
+;              | |             | |
+; start bit----+ +--lsb   msb--+ +----stop bit
+;
+;we'll start timer #1 in 16 bit mode at the transition between the
+;start bit and the LSB and stop it between the MBS and stop bit.
+;That will give approx the number of cpu cycles for 8 bits.  Divide
+;by 8 for one bit and by 16 since the built-in UART takes 16 timer
+;overflows for each bit.  We need to be careful about roundoff during
+;division and the result has to be inverted since timer #1 counts up.  Of
+;course, timer #1 gets used in 8-bit auto reload mode for generating the
+;built-in UART's baud rate once we know what the reload value should be.
+*/
+
+void autobaud ()
+{
+
+        /* get timer #1 ready for action (16 bit mode) */
+        TMOD=0x11;
+        TCON = 0;
+        TH1 = TL1 = 0;
+        
+        /* wait for start bit */
+autobaud2:
+        while(RXD) ; 
+
+        /*  check it a few more times to make
+             sure we don't trigger on some noise*/
+        if (RXD) goto autobaud2;
+        if (RXD) goto autobaud2;
+        if (RXD) goto autobaud2;
+        if (RXD) goto autobaud2;
+
+        /* wait for bit #0 to begin      */
+        while (!RXD);
+        TR1 = 1; /* start the timer */
+        while (RXD);             // wait for bit #1 to begin
+        while(!RXD);             // wait for bit #2 to begin
+        while(RXD);              // wait for bit #4 to begin
+        while (!RXD);            // wait for stop bit to begin
+        TR1 = 0;                 // stop timing
+
+        /* ;grab bit 7... it's the lsb we want */
+        TH1 = (TH1 << 1) | (TL1 >> 7);
+
+        /* round off if necessary */
+        TH1 = (TH1 << 1) | ((TL1 >> 6) & 0x01);
+
+        /* invert since timer #1 will count up */
+        TH1 = ~TH1;
+
+        /* now TH1 has the correct reload value (I hope) */
+        TH1++ ;
+
+        TL1 = TH1;
+        TMOD =  0x21     ;      // set timer #1 for 8 bit auto-reload
+        PCON =  0x80     ;      // configure built-in uart
+        SCON =  0x52     ;
+}