main.c

开源DOS的C代码源程序

/****************************************************************/
/*                                                              */
/*                           main.c                             */
/*                            DOS-C                             */
/*                                                              */
/*                    Main Kernel Functions                     */
/*                                                              */
/*                   Copyright (c) 1995, 1996                   */
/*                      Pasquale J. Villani                     */
/*                      All Rights Reserved                     */
/*                                                              */
/* This file is part of DOS-C.                                  */
/*                                                              */
/* DOS-C 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.                    */
/*                                                              */
/* DOS-C 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 DOS-C; see the file COPYING.  If not,     */
/* write to the Free Software Foundation, Inc.,                 */
/* 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA.     */
/****************************************************************/

#include "portab.h"
#include "init-mod.h"
#include "dyndata.h"

#ifdef VERSION_STRINGS
static BYTE *mainRcsId =
    "$Id: main.c,v 1.81 2004/05/23 22:04:42 bartoldeman Exp $";
#endif

static char copyright[] =
    "(C) Copyright 1995-2004 Pasquale J. Villani and The FreeDOS Project.\n"
    "All Rights Reserved. This is free software and comes with ABSOLUTELY NO\n"
    "WARRANTY; you can redistribute it and/or modify it under the terms of the\n"
    "GNU General Public License as published by the Free Software Foundation;\n"
    "either version 2, or (at your option) any later version.\n";

struct _KernelConfig InitKernelConfig BSS_INIT({0});

STATIC VOID InitIO(void);

STATIC VOID update_dcb(struct dhdr FAR *);
STATIC VOID init_kernel(VOID);
STATIC VOID signon(VOID);
STATIC VOID kernel(VOID);
STATIC VOID FsConfig(VOID);
STATIC VOID InitPrinters(VOID);
STATIC VOID InitSerialPorts(VOID);
STATIC void CheckContinueBootFromHarddisk(void);
STATIC void setup_int_vectors(void);

#ifdef _MSC_VER
BYTE _acrtused = 0;

__segment DosDataSeg = 0;       /* serves for all references to the DOS DATA segment 
                                   necessary for MSC+our funny linking model
                                 */
__segment DosTextSeg = 0;

#endif

struct lol FAR *LoL = &DATASTART;

VOID ASMCFUNC FreeDOSmain(void)
{
  unsigned char drv;
  unsigned char FAR *p;

#ifdef _MSC_VER
  extern FAR prn_dev;
  DosDataSeg = (__segment) & DATASTART;
  DosTextSeg = (__segment) & prn_dev;
#endif

  /* clear the Init BSS area (what normally the RTL does */
  memset(_ib_start, 0, _ib_end - _ib_start);

                        /*  if the kernel has been UPX'ed,
                                CONFIG info is stored at 50:e2 ..fc
                            and the bootdrive (passed from BIOS)
                            at 50:e0
                        */

  drv = LoL->BootDrive + 1;
  p = MK_FP(0, 0x5e0);
  if (fmemcmp(p+2,"CONFIG",6) == 0)      /* UPX */
  {
    fmemcpy(&InitKernelConfig, p+2, sizeof(InitKernelConfig));

    drv = *p + 1;
    *(DWORD FAR *)(p+2) = 0;
  }
  else
  {
    *p = drv - 1;
    fmemcpy(&InitKernelConfig, &LowKernelConfig, sizeof(InitKernelConfig));
  }

  if (drv >= 0x80)
    drv = 3; /* C: */
  LoL->BootDrive = drv;

  setup_int_vectors();

  CheckContinueBootFromHarddisk();

  signon();
  init_kernel();

#ifdef DEBUG
  /* Non-portable message kludge alert!   */
  printf("KERNEL: Boot drive = %c\n", 'A' + LoL->BootDrive - 1);
#endif

  DoInstall();

  kernel();
}

/*
    InitializeAllBPBs()
    
    or MakeNortonDiskEditorHappy()

    it has been determined, that FDOS's BPB tables are initialized,
    only when used (like DIR H:).
    at least one known utility (norton DE) seems to access them directly.
    ok, so we access for all drives, that the stuff gets build
*/
void InitializeAllBPBs(VOID)
{
  static char filename[] = "A:-@[e-mail]";
  int drive, fileno;
  for (drive = 'C'; drive < 'A' + LoL->nblkdev; drive++)
  {
    filename[0] = drive;
    if ((fileno = open(filename, O_RDONLY)) >= 0)
      close(fileno);
  }
}

STATIC void PSPInit(void)
{
  psp far *p = MK_FP(DOS_PSP, 0);

  /* Clear out new psp first                              */
  fmemset(p, 0, sizeof(psp));

  /* initialize all entries and exits                     */
  /* CP/M-like exit point                                 */
  p->ps_exit = 0x20cd;

  /* CP/M-like entry point - call far to special entry    */
  p->ps_farcall = 0x9a;
  p->ps_reentry = MK_FP(0, 0x30 * 4);
  /* unix style call - 0xcd 0x21 0xcb (int 21, retf)      */
  p->ps_unix[0] = 0xcd;
  p->ps_unix[1] = 0x21;
  p->ps_unix[2] = 0xcb;

  /* Now for parent-child relationships                   */
  /* parent psp segment                                   */
  p->ps_parent = FP_SEG(p);
  /* previous psp pointer                                 */
  p->ps_prevpsp = MK_FP(0xffff,0xffff);

  /* Environment and memory useage parameters             */
  /* memory size in paragraphs                            */
  /*  p->ps_size = 0; clear from above                    */
  /* environment paragraph                                */
  p->ps_environ = DOS_PSP + 8;
  /* terminate address                                    */
  p->ps_isv22 = getvec(0x22);
  /* break address                                        */
  p->ps_isv23 = getvec(0x23);
  /* critical error address                               */
  p->ps_isv24 = getvec(0x24);

  /* user stack pointer - int 21                          */
  /* p->ps_stack = NULL; clear from above                 */

  /* File System parameters                               */
  /* maximum open files                                   */
  p->ps_maxfiles = 20;
  fmemset(p->ps_files, 0xff, 20);

  /* open file table pointer                              */
  p->ps_filetab = p->ps_files;

  /* first command line argument                          */
  /* p->ps_fcb1.fcb_drive = 0; already set                */
  fmemset(p->ps_fcb1.fcb_fname, ' ', FNAME_SIZE + FEXT_SIZE);
  /* second command line argument                         */
  /* p->ps_fcb2.fcb_drive = 0; already set                */
  fmemset(p->ps_fcb2.fcb_fname, ' ', FNAME_SIZE + FEXT_SIZE);

  /* local command line                                   */
  /* p->ps_cmd.ctCount = 0;     command tail, already set */
  p->ps_cmd.ctBuffer[0] = 0xd; /* command tail            */
}

#ifndef __WATCOMC__
/* for WATCOMC we can use the ones in task.c */
intvec getvec(unsigned char intno)
{
  intvec iv;
  disable();
  iv = *(intvec FAR *)MK_FP(0,4 * (intno));
  enable();
  return iv;
}

void setvec(unsigned char intno, intvec vector)
{
  disable();
  *(intvec FAR *)MK_FP(0,4 * intno) = vector;
  enable();
}
#endif

STATIC void setup_int_vectors(void)
{
  static struct vec
  {
    unsigned char intno;
    size_t handleroff;
  } vectors[] =
    {
      /* all of these are in the DOS DS */
      { 0x0, FP_OFF(int0_handler) },   /* zero divide */
      { 0x1, FP_OFF(empty_handler) },  /* single step */
      { 0x3, FP_OFF(empty_handler) },  /* debug breakpoint */
      { 0x6, FP_OFF(int6_handler) },   /* invalid opcode */
      { 0x20, FP_OFF(int20_handler) },
      { 0x21, FP_OFF(int21_handler) },
      { 0x22, FP_OFF(int22_handler) },
      { 0x24, FP_OFF(int24_handler) },
      { 0x25, FP_OFF(low_int25_handler) },
      { 0x26, FP_OFF(low_int26_handler) },
      { 0x27, FP_OFF(int27_handler) },
      { 0x28, FP_OFF(int28_handler) },
      { 0x2a, FP_OFF(int2a_handler) },
      { 0x2f, FP_OFF(int2f_handler) }
    };
  struct vec *pvec;
  int i;

  for (i = 0x23; i <= 0x3f; i++)
    setvec(i, empty_handler);
  for (pvec = vectors; pvec < vectors + (sizeof vectors/sizeof *pvec); pvec++)
    setvec(pvec->intno, (intvec)MK_FP(FP_SEG(empty_handler), pvec->handleroff));
  pokeb(0, 0x30 * 4, 0xea);
  pokel(0, 0x30 * 4 + 1, (ULONG)cpm_entry);

  /* these two are in the device driver area LOWTEXT (0x70) */
  setvec(0x1b, got_cbreak);
  setvec(0x29, int29_handler);  /* required for printf! */
}

STATIC void init_kernel(void)
{
  COUNT i;

  LoL->os_setver_major = LoL->os_major = MAJOR_RELEASE;
  LoL->os_setver_minor = LoL->os_minor = MINOR_RELEASE;

  /* Init oem hook - returns memory size in KB    */
  ram_top = init_oem();

  /* move kernel to high conventional RAM, just below the init code */
#ifdef __WATCOMC__
  lpTop = MK_FP(_CS, 0);
#else
  lpTop = MK_FP(_CS - (FP_OFF(_HMATextEnd) + 15) / 16, 0);
#endif

  MoveKernel(FP_SEG(lpTop));
  lpTop = MK_FP(FP_SEG(lpTop) - 0xfff, 0xfff0);

  /* Initialize IO subsystem                                      */
  InitIO();
  InitPrinters();
  InitSerialPorts();

  init_PSPSet(DOS_PSP);
  set_DTA(MK_FP(DOS_PSP, 0x80));
  PSPInit();

  Init_clk_driver();

  /* Do first initialization of system variable buffers so that   */
  /* we can read config.sys later.  */
  LoL->lastdrive = Config.cfgLastdrive;

  /*  init_device((struct dhdr FAR *)&blk_dev, NULL, 0, &ram_top); */
  blk_dev.dh_name[0] = dsk_init();

  PreConfig();

  /* Number of units */
  if (blk_dev.dh_name[0] > 0)
    update_dcb(&blk_dev);

  /* Now config the temporary file system */
  FsConfig();

  /* Now process CONFIG.SYS     */
  DoConfig(0);
  DoConfig(1);

  /* initialize near data and MCBs */
  PreConfig2();
  /* and process CONFIG.SYS one last time for device drivers */
  DoConfig(2);


  /* Close all (device) files */
  for (i = 0; i < 20; i++)
    close(i);

  /* and do final buffer allocation. */
  PostConfig();

  /* Init the file system one more time     */
  FsConfig();
  
  configDone();

  InitializeAllBPBs();
}

STATIC VOID FsConfig(VOID)
{
  struct dpb FAR *dpb = LoL->DPBp;
  int i;

  /* Initialize the current directory structures    */
  for (i = 0; i < LoL->lastdrive; i++)
  {
    struct cds FAR *pcds_table = &LoL->CDSp[i];

    fmemcpy(pcds_table->cdsCurrentPath, "A:\\\0", 4);

    pcds_table->cdsCurrentPath[0] += i;

    if (i < LoL->nblkdev && (ULONG) dpb != 0xffffffffl)
    {
      pcds_table->cdsDpb = dpb;
      pcds_table->cdsFlags = CDSPHYSDRV;
      dpb = dpb->dpb_next;
    }
    else
    {
      pcds_table->cdsFlags = 0;
    }
    pcds_table->cdsStrtClst = 0xffff;
    pcds_table->cdsParam = 0xffff;
    pcds_table->cdsStoreUData = 0xffff;
    pcds_table->cdsJoinOffset = 2;
  }

  /* Log-in the default drive. */
  init_setdrive(LoL->BootDrive - 1);

  /* The system file tables need special handling and are "hand   */
  /* built. Included is the stdin, stdout, stdaux and stdprn. */
  /* a little bit of shuffling is necessary for compatibility */

  /* sft_idx=0 is /dev/aux                                        */
  open("AUX", O_RDWR);

  /* handle 1, sft_idx=1 is /dev/con (stdout) */
  open("CON", O_RDWR);