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Subversion Repositories openrisc_2011-10-31

[/] [openrisc/] [trunk/] [rtos/] [rtems/] [tools/] [cpu/] [sh/] [sci.c] - Blame information for rev 637

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Line No. Rev Author Line
1 30 unneback
/*
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 * Copyright (c) 1998 Ralf Corsepius (corsepiu@faw.uni-ulm.de)
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 *
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 * See the file COPYING for copyright notice.
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 */
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#include <math.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include "sci.h"
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/*
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   n .. baudrate generator source 0,1,2,3
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   N .. BRR setting (0..255)
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   Phi .. processor baud rate
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   B .. bitrate
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 */
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typedef struct sci_tab {
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  unsigned int  B ;
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  unsigned int  n ;
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  int           N ;
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  double        err ;
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  } sci_tab_t ;
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static unsigned int bitrate [] = {
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  50,
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  75,
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  110,
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  134,
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  150,
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  200,
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  300,
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  600,
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  1200,
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  1800,
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  2400,
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  4800,
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  9600,
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  19200,
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  38400,
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  57600,
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  115200,
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  230400,
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  460800
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};
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static sci_tab_t test_array[4] ;
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static void Compute(
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  unsigned int n,
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  unsigned int B,
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  double   Phi,
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  struct sci_tab *entry )
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{
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  int    a = ( 32 << ( 2 * n ) ) * B ;
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  entry->n = n ;
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  entry->B = B ;
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  entry->N = rint( ( Phi / a ) - 1.0 ) ;
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  if ( ( entry->N > 0 ) && ( entry->N < 256 ) )
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    entry->err =
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      ( ( Phi / ( (entry->N + 1) * a ) - 1.0 ) * 100.0 );
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  else
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  {
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    entry->err = 100.0 ;
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    entry->n = 255 ;
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    entry->N = 0 ;
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  }
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}
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static sci_tab_t *SelectN(
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  unsigned int  B,
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  double        Phi )
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{
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  unsigned int i ;
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  struct sci_tab* best = NULL ;
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  for ( i = 0 ; i < 4 ; i++ )
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  {
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    double err ;
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    Compute( i, B, Phi, &test_array[i] );
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    err = fabs( test_array[i].err );
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    if ( best )
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    {
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      if ( err < fabs( best->err ) )
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        best = &test_array[i] ;
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    }
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    else
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      best = &test_array[i] ;
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  }
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  return best ;
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}
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int shgen_gensci(
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  FILE          *file,
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  double        Phi ) /* Processor frequency [Hz] */
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{
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  unsigned int i ;
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  fprintf( file,
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    "/*\n * Bitrate table for the serial devices (sci) of the SH at %.3f MHz\n"
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    " */\n\n", Phi / 1000000.0 );
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  fprintf( file,
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    "/*\n"
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    " * n     .. SMR bits 0,1 : baud rate generator clock source\n"
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    " * N     .. BRR bits 0..7: setting for baud rate generator\n"
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    " * error .. percentual error to nominal bitrate\n"
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    " *   Hitachi's HW manual recommends bitrates with an error less than 1%%\n"
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    " *   We experienced values less than 2%% to be stable\n"
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    " */\n\n" );
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  fprintf( file, "#include <termios.h>\n\n" );
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  fprintf( file,
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    "static struct sci_bitrate_t {\n"
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    "  unsigned char n ;\n"
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    "  unsigned char N ;\n"
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    "} _sci_bitrates[] = {\n"
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    "/*  n    N      error */\n" );
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  for ( i = 0 ; i < sizeof(bitrate)/sizeof(int) ; i++ )
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  {
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    struct sci_tab* best = SelectN( bitrate[i], Phi );
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    if ( i > 0 )
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      fprintf( file, ",\n" );
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    fprintf( file, "  { %1d, %3d } /* %+7.2f%% ; B%d ",
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      best->n,
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      best->N,
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      best->err,
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      best->B );
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    if ( best->n > 3 )
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      fprintf( file, "(unusable) " );
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    fprintf( file, "*/" );
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  }
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  fprintf( file, "\n};\n\n" );
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  fprintf( file,
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    "int _sci_get_brparms( \n"
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    "  tcflag_t      cflag,\n"
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    "  unsigned char *smr,\n"
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    "  unsigned char *brr )\n"
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    "{\n"
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    "  unsigned int offset ;\n\n"
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    "  offset = ( cflag & ( CBAUD & ~CBAUDEX ) )\n"
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    "    + ( ( cflag & CBAUDEX ) ? B38400 : 0 );\n"
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    "  if ( offset == 0 ) return -1 ;\n"
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    "  offset-- ;\n\n"
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    "  if ( _sci_bitrates[offset].n > 3 )  return -1;\n\n"
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    "  *smr &= ~0x03;\n"
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    "  *smr |= _sci_bitrates[offset].n;\n"
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    "  *brr =  _sci_bitrates[offset].N;\n\n"
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    "  return 0;\n"
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    "}\n" );
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  return 0 ;
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}

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