Subversion Repositories SvarDOS

/* This file is part of the svarlang project and is published under the terms

 * of the MIT license.

 *

 * Copyright (C) 2021-2023 Mateusz Viste

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included in

 * all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE

 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER

 * DEALINGS IN THE SOFTWARE.

 */

/* if WITHSTDIO is enabled, then remap file operations to use the standard

 * stdio amenities */

#ifdef WITHSTDIO

#include <stdio.h>   /* FILE, fopen(), fseek(), etc */

typedef FILE* FHANDLE;

#define FOPEN(x) fopen(x, "rb")

#define FCLOSE(x) fclose(x)

#define FSEEK(f,b) fseek(f,b,SEEK_CUR)

#define FREAD(f,t,b) fread(t, 1, b, f)

#else

#include <i86.h>  /* FP_SEG, FP_OFF */

typedef unsigned short FHANDLE;

#endif

#include "svarlang.h"

/* supplied through DEFLANG.C */

extern char svarlang_mem[];

extern unsigned short svarlang_dict[];

extern const unsigned short svarlang_memsz;

extern const unsigned short svarlang_string_count;

const char *svarlang_strid(unsigned short id) {

  unsigned short left = 0, right = svarlang_string_count - 1, x;

  unsigned short v;

  if (svarlang_string_count == 0) return("");

  while (left <= right) {

    x = left + ((right - left ) >> 2);

    v = svarlang_dict[x * 2];

    if (id == v) return(svarlang_mem + svarlang_dict[x * 2 + 1]);

    if (id > v) {

      left = x + 1;

    } else {

      right = x - 1;

    }

  }

  return("");

}

/* routines below are simplified (dos-based) versions of the libc FILE-related

 * functions. Using them avoids a dependency on FILE, hence makes the binary

 * smaller if the application does not need to pull fopen() and friends */

#ifndef WITHSTDIO

static unsigned short FOPEN(const char *s) {

  unsigned short fname_seg = FP_SEG(s);

  unsigned short fname_off = FP_OFF(s);

  unsigned short res = 0; /* fd 0 is already used by stdout so it's a good error value */

  _asm {

    push dx

    push ds

    mov ax, fname_seg

    mov dx, fname_off

    mov ds, ax

    mov ax, 0x3d00  /* open file, read-only (fname at DS:DX) */

    int 0x21

    pop ds

    jc ERR

    mov res, ax

    ERR:

    pop dx

  }

  return(res);

}

static void FCLOSE(unsigned short handle) {

  _asm {

    mov ah, 0x3e

    mov bx, handle

    int 0x21

  }

}

static unsigned short FREAD(unsigned short handle, void *buff, unsigned short bytes) {

  unsigned short buff_seg = FP_SEG(buff);

  unsigned short buff_off = FP_OFF(buff);

  unsigned short res = 0;

  _asm {

    push bx

    push cx

    push dx

    mov bx, handle

    mov cx, bytes

    mov dx, buff_off

    mov ax, buff_seg

    push ds

    mov ds, ax

    mov ah, 0x3f    /* read cx bytes from file handle bx to DS:DX */

    int 0x21

    pop ds

    jc ERR

    mov res, ax

    ERR:

    pop dx

    pop cx

    pop bx

  }

  return(res);

}

static void FSEEK(unsigned short handle, unsigned short bytes) {

  _asm {

    mov ax, 0x4201  /* move file pointer from cur pos + CX:DX */

    mov bx, handle

    xor cx, cx

    mov dx, bytes

    int 0x21

  }

}

#endif

int svarlang_load(const char *fname, const char *lang) {

  unsigned short langid;

  unsigned short buff16[2];

  FHANDLE fd;

  signed char exitcode = 0;

  struct {

    unsigned long sig;

    unsigned short string_count;

  } hdr;

  langid = *((unsigned short *)lang);

  langid &= 0xDFDF; /* make sure lang is upcase */

  fd = FOPEN(fname);

  if (!fd) return(-1);

  /* read hdr, sig should be "SvL\x1a" (0x1a4c7653) */

  if ((FREAD(fd, &hdr, 6) != 6) || (hdr.sig != 0x1a4c7653L) || (hdr.string_count != svarlang_string_count)) {

    exitcode = -2;

    goto FCLOSE_AND_EXIT;

  }

  for (;;) {

    /* read next lang id and string table size in file */

    if (FREAD(fd, buff16, 4) != 4) {

      exitcode = -3;

      goto FCLOSE_AND_EXIT;

    }

    /* is it the lang I am looking for? */

    if (buff16[0] == langid) break;

    /* skip to next lang (in two steps to avoid a potential uint16 overflow) */

    FSEEK(fd, svarlang_string_count * 4);

    FSEEK(fd, buff16[1]);

  }

  /* load dictionary & strings, but only if I have enough memory space */

  if ((buff16[1] >= svarlang_memsz)

   || (FREAD(fd, svarlang_dict, svarlang_string_count * 4) != svarlang_string_count * 4)

   || (FREAD(fd, svarlang_mem, buff16[1]) != buff16[1])) {

    exitcode = -4;

  }

  FCLOSE_AND_EXIT:

  FCLOSE(fd);

  return(exitcode);

}