/*************************************************************************
 *                                                                       *
 * Open Dynamics Engine, Copyright (C) 2001,2002 Russell L. Smith.       *
 * All rights reserved.  Email: russ@q12.org   Web: www.q12.org          *
 *                                                                       *
 * This library is free software; you can redistribute it and/or         *
 * modify it under the terms of EITHER:                                  *
 *   (1) The GNU Lesser General Public License as published by the Free  *
 *       Software Foundation; either version 2.1 of the License, or (at  *
 *       your option) any later version. The text of the GNU Lesser      *
 *       General Public License is included with this library in the     *
 *       file LICENSE.TXT.                                               *
 *   (2) The BSD-style license that is included with this library in     *
 *       the file LICENSE-BSD.TXT.                                       *
 *                                                                       *
 * 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 files    *
 * LICENSE.TXT and LICENSE-BSD.TXT for more details.                     *
 *                                                                       *
 *************************************************************************/

/*

this program discovers some system configuration stuff, prior to compiling
ODE. the usage is:

  configurator <config.h-file-to-generate> <compiler-command-line>
	<delete-command-line> <THIS_DIR-variable>

this program looks long, but it really has an extremely simple structure and
should be very easy for anyone to modify. it should be very portable as it
is written in straight ANSI C and only uses the following library functions:
  * printf
  * fopen (assumes 0 returned on failure)
  * fclose
  * fprintf
  * system
  * exit
except where stated, we do not assume anything about the return codes from
these functions.

why didn't i just use GNU autoconf? :
  * autoconf needs a bourne shell and a bunch of other tools that windows
    users may not have.
  * i like reinventing the wheel.

*/

#include <stdio.h>

/****************************************************************************/
/* project constants */

#define SETUP_SHLIB_DEFS \
  "#ifndef SHAREDLIBIMPORT\n" \
  "#define SHAREDLIBIMPORT\n" \
  "#endif\n" \
  "#ifndef SHAREDLIBEXPORT\n" \
  "#define SHAREDLIBEXPORT\n" \
  "#endif\n"

/* the config.h header */
char *config_h_part1 =
"/* per-machine configuration. this file is automatically generated. */\n"
"\n"
"#ifndef _ODE_CONFIG_H_\n"
"#define _ODE_CONFIG_H_\n"
"\n"
"/* shared lib definitions */\n"
SETUP_SHLIB_DEFS
"\n"
"/* standard system headers */\n";


char *config_h_part2 =
"\n"
"#ifdef __cplusplus\n"
"extern \"C\" {\n"
"#endif\n"
"\n";

/* the config.h footer */
char *config_h_footer =
"#ifdef __cplusplus\n"
"}\n"
"#endif\n"
"#endif\n";

/****************************************************************************/
/* implementations of some string functions. these are prefixed with 'x'
 * to prevent any conflicts with built-in functions.
 */

#define strcpy xstrcpy
void xstrcpy (char *dest, char *src)
{
  while (*src) *dest++ = *src++;
  *dest = 0;
}


#define strcat xstrcat
void xstrcat (char *dest, char *src)
{
  while (*dest) dest++;
  while (*src) *dest++ = *src++;
  *dest = 0;
}

/****************************************************************************/
/* utility functions */

/* print an error message and exit */

void fatal_error (char *message)
{
  printf ("\n*** configurator failed: %s.\n\n"
	  "please fix your configuration and try again.\n"
	  "if you have to fix the configurator program or the makefiles, "
	  "please email\n"
	  "your changes to the ODE mailing list (ode@q12.org).\n\n", message);
  exit (0);
}


/* open a file, generate an error if it can't be done */

FILE * xfopen (char *filename, char *mode)
{
  FILE *f;
  f = fopen (filename,mode);
  if (!f) fatal_error ("can not open a file");
  return f;
}


/* return 1 if the file exists or 0 if not */

int file_exists (char *filename)
{
  FILE *f;
  f = fopen (filename,"rb");
  if (f) fclose (f);
  return (f != 0);
}


/* write a string to a new file */

void write_to_file (char *filename, char *s)
{
  FILE *f = xfopen (filename,"wt");
  fprintf (f,"%s",s);
  fclose (f);
}


/* write a comment to a header file */

void write_header_comment (FILE *file, char *description)
{
  fprintf (file,"/* %s */\n",description);
  printf ("%s ...\n",description);
}


/* delete a file */

char *delete_cmd_line = 0;
void delete_file (char *filename)
{
  char cmd[1000];
  strcpy (cmd,delete_cmd_line);
  strcat (cmd," ");
  strcat (cmd,filename);
  printf ("%s\n",cmd);
  system (cmd);
}


/* run a compile command */

char *compile_cmd_line = 0;
void compile (char *output, char *input)
{
  char cmd[1000];
  strcpy (cmd,compile_cmd_line);
  strcat (cmd,output);
  strcat (cmd," ");
  strcat (cmd,input);
  printf ("%s\n",cmd);
  system (cmd);
}


/* run a program we've just compiled */

char *run_prefix = "";
void run (char *filename)
{
  char cmd[1000];
  strcpy (cmd,run_prefix);
  strcat (cmd,filename);
  printf ("%s\n",cmd);
  system (cmd);
}

/****************************************************************************/
/* system tests */

void check_if_this_is_a_pentium (FILE *file)
{
  write_header_comment (file,"is this a pentium on a gcc-based platform?");
  write_to_file ("ctest.c",
		 "int main() {\n"
		 "  asm (\"mov $0,%%eax\\n cpuid\\n\" : : : \"%eax\");\n"
		 "  return 0;\n"
		 "}\n");
  delete_file ("ctest.exe");
  compile ("ctest.exe","ctest.c");
  if (file_exists ("ctest.exe")) {
    fprintf (file,"#define PENTIUM 1\n\n");
  }
  else {
    fprintf (file,"/* #define PENTIUM 1 -- not a pentium */\n\n");
  }

  delete_file ("ctest.c");
  delete_file ("ctest.exe");
}

/****************************************************************************/
/* tests: standard headers */

void get_all_standard_headers (FILE *file)
{
  int i;
  FILE *f;
  char *header[7] = {"stdio.h", "stdlib.h", "math.h", "string.h",
		     "stdarg.h", "malloc.h", "alloca.h"};

  for (i=0; i < sizeof(header)/sizeof(char*); i++) {
    FILE *f = xfopen ("ctest.c","wt");
    fprintf (f,"#include <%s>\nint main() { return 0; }\n",header[i]);
    fclose (f);
    delete_file ("ctest.exe");
    compile ("ctest.exe","ctest.c");
    if (file_exists ("ctest.exe")) {
      fprintf (file,"#include <%s>\n",header[i]);
    }
  }

  delete_file ("ctest.c");
  delete_file ("ctest.exe");
}

/****************************************************************************/
/* tests: typedefs and constants for ODE */

void get_ODE_integer_typedefs (FILE *file)
{
  write_header_comment (file,"integer types (we assume int >= 32 bits)");
  if (sizeof(char) != 1) fatal_error ("expecting sizeof(char) == 1");
  if (sizeof(int) < 4) fatal_error ("expecting sizeof(int) >= 4");
  fprintf (file,"typedef char int8;\ntypedef unsigned char uint8;\n");
  if (sizeof(short) == 4) {
    fprintf (file,"typedef short int32;\ntypedef unsigned short uint32;\n");
  }
  else if (sizeof(int) == 4) {
    fprintf (file,"typedef int int32;\ntypedef unsigned int uint32;\n");
  }
  else {
    fatal_error ("can not find 4 byte integer type");
  }
  fprintf (file,"\n"
	   "/* an integer type that we can safely cast a pointer to and\n"
	   " * from without loss of bits.\n"
	   " */\n");
  if (sizeof(short) == sizeof(void*)) {
    fprintf (file,"typedef unsigned short intP;\n");
  }
  else if (sizeof(int) == sizeof(void*)) {
    fprintf (file,"typedef unsigned int intP;\n");
  }
  else if (sizeof(long int) == sizeof(void*)) {
    fprintf (file,"typedef unsigned long int intP;\n");
  }
  fprintf (file,"\n");
}


void get_ODE_float_stuff (FILE *file)
{
  char *suffix,*type;
  int i;
  FILE *f;

#define SHARED_LIB_SPEC_DECISION \
    "#if defined SHARED_CONFIG_H_INCLUDED_FROM_DEFINING_FILE\n" \
    "  #define GLOBAL_SHAREDLIB_SPEC SHAREDLIBEXPORT\n" \
    "#else \n" \
    "  #define GLOBAL_SHAREDLIB_SPEC SHAREDLIBIMPORT\n" \
    "#endif\n"

#define UNDEF_SHAREDLIB_SPEC "\n#undef GLOBAL_SHAREDLIB_SPEC\n"

#ifdef dSINGLE

#define INFBYTES SHARED_LIB_SPEC_DECISION "union dInfBytes { unsigned char c[4]; float f; };\nextern GLOBAL_SHAREDLIB_SPEC union dInfBytes dInfinityValue;\n#define dInfinity (dInfinityValue.f)"

  char *inc[6]	= {"#include <math.h>",
		   "#include <math.h>",
		   "",
		   "",
		   "",
		   ""};
  char *decl[6] = {
    "SHAREDLIBEXPORT double dInfinityValue = HUGE_VALF;",
    "SHAREDLIBEXPORT double dInfinityValue = HUGE_VAL;",
    "SHAREDLIBEXPORT union dInfBytes dInfinityValue = {{0x7f,0x80,0,0}};",
    "SHAREDLIBEXPORT union dInfBytes dInfinityValue = {{0,0,0x80,0x7f}};",
    "SHAREDLIBEXPORT double dInfinityValue = 1.0f/0.0f;",
    "SHAREDLIBEXPORT double dInfinityValue = 1e20f;"};
  char *inf[6]	= {
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC,
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC,
    INFBYTES UNDEF_SHAREDLIB_SPEC,
    INFBYTES UNDEF_SHAREDLIB_SPEC,
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC,
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC};

#else /* not dSINGLE, must be dDOUBLE */

#define INFBYTES SHARED_LIB_SPEC_DECISION "union dInfBytes { unsigned char c[8]; double d; };\nextern GLOBAL_SHAREDLIB_SPEC union dInfBytes dInfinityValue;\n#define dInfinity (dInfinityValue.d)"

  char *inc[5]	= {
    "#include <math.h>",
    "",
    "",
    "",
    ""};
  char *decl[5] = {
    "SHAREDLIBEXPORT double dInfinityValue = HUGE_VAL;",
    "SHAREDLIBEXPORT union dInfBytes dInfinityValue = {{0x7f,0xf0,0,0,0,0,0,0}};",
    "SHAREDLIBEXPORT union dInfBytes dInfinityValue = {{0,0,0,0,0,0,0xf0,0x7f}};",
    "SHAREDLIBEXPORT double dInfinityValue = 1.0/0.0;",
    "SHAREDLIBEXPORT double dInfinityValue = 1e20;"};
  char *inf[5]	= {
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC,
    INFBYTES UNDEF_SHAREDLIB_SPEC,
    INFBYTES UNDEF_SHAREDLIB_SPEC,
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC,
    SHARED_LIB_SPEC_DECISION "extern GLOBAL_SHAREDLIB_SPEC double dInfinityValue;\n#define dInfinity dInfinityValue" UNDEF_SHAREDLIB_SPEC};
#endif

  write_header_comment (file,"select the base floating point type");
#ifdef dSINGLE
  fprintf (file,"#define dSINGLE 1\n\n");
  type = "float";
  suffix = "f";
#else
  fprintf (file,"#define dDOUBLE 1\n\n");
  type = "double";
  suffix = "";
#endif

  /* infinity */
  write_header_comment (file,"the floating point infinity");

  /* try the different infinity constants until one works */
  for (i=0; i < sizeof(inf)/sizeof(char*); i++) {
    f = xfopen ("ctest.c","wt");
    fprintf (f,
	     "#include <stdio.h>\n"
	     "#define SHARED_CONFIG_H_INCLUDED_FROM_DEFINING_FILE 1\n"
	     SETUP_SHLIB_DEFS
	     "%s\n"
	     "%s\n"
	     "%s\n"
	     "int main() {\n"
	     "	if (dInfinity > 1e10%s && -dInfinity < -1e10%s &&\n"
	     "	    -dInfinity < dInfinity) {\n"
	     "	  FILE *f = fopen (\"data\",\"wt\");\n"
	     "	  fprintf (f,\"foo\\n\");\n"
	     "	  fclose (f);\n"
	     "	}\n"
	     "	return 0;\n"
	     "}\n"
	     ,inc[i],inf[i],decl[i],suffix,suffix);
    fclose (f);
    delete_file ("data");
    compile ("ctest.exe","ctest.c");
    run ("ctest.exe");
    if (file_exists ("data")) {
      fprintf (file,"#define DINFINITY_DECL %s\n",decl[i]);
      fprintf (file,"%s\n\n",inf[i]);
      delete_file ("ctest.c");
      delete_file ("ctest.exe");
      delete_file ("data");
      return;
    }
  }

  fatal_error ("can't determine dInfinity constant");
}

/****************************************************************************/

int main (int argc, char **argv)
{
  FILE *file;

  if (argc < 4 || argc > 5)
    fatal_error ("configurator expects 3 or 4 arguments");
  compile_cmd_line = argv[2];
  delete_cmd_line = argv[3];
  if (argc >= 5) run_prefix = argv[4];

  /* check some defines we should have been compiled with */
#if !defined(dSINGLE) && !defined(dDOUBLE)
  fatal_error ("you must set PRECISION to either SINGLE or DOUBLE");
#endif

  file = xfopen (argv[1],"wt");
  fprintf (file,config_h_part1);
  get_all_standard_headers (file);
  fprintf (file,config_h_part2);
  check_if_this_is_a_pentium (file);
  get_ODE_integer_typedefs (file);
  get_ODE_float_stuff (file);
  fprintf (file,config_h_footer);
  fclose (file);

  printf ("\n*** configurator succeeded ***\n\n");
  return 0;
}