Subversion Repositories SvarDOS

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

 * of the MIT license.

 *

 * Copyright (C) 2021-2024 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) {

      if (x == 65535) goto not_found;

      left = x + 1;

    } else {

      if (x == 0) goto not_found;

      right = x - 1;

    }

  }

not_found:

  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

 * I use pragma aux directives for more compact size. open-watcom only. */

#ifndef WITHSTDIO

static unsigned short FOPEN(const char far *s);

#pragma aux FOPEN = \

"push ds" \

"push es" \

"pop ds" \

"mov ax, 0x3D00" /* open file, read-only (fname at DS:DX) */ \

"int 0x21" \

"jnc DONE" \

"xor ax, ax"     /* return 0 on error */ \

"DONE:" \

"pop ds" \

parm [es dx] \

value [ax];

static void FCLOSE(unsigned short handle);

#pragma aux FCLOSE = \

"mov ah, 0x3E" \

"int 0x21" \

modify [ax]  /* AX might contain an error code on failure */ \

parm [bx]

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

#pragma aux FREAD = \

"push ds" \

"push es" \

"pop ds" \

"mov ah, 0x3F"    /* read cx bytes from file handle bx to DS:DX */ \

"int 0x21" \

"jnc ERR" \

"xor ax, ax"      /* return 0 on error */ \

"ERR:" \

"pop ds" \

parm [bx] [es dx] [cx] \

value [ax]

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

#pragma aux FSEEK = \

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

"xor cx, cx" \

"int 0x21" \

parm [bx] [dx] \

modify [ax cx dx]

#endif

#ifdef MVUCOMP_ASM

static void mvucomp_asm(unsigned short bufseg, unsigned short dst, unsigned short src, unsigned short complen);

#pragma aux mvucomp_asm = \

"    push ds"\

\

     /* ds:si = compressed stream */     \

     /* es:di = output location */       \

     /* bx = len of compressed stream */ \

"    shr bx, 1" /* convert byte length to number of words */ \

"    cld" /* make sure stosw and friends move forward */ \

     /* set ds = es = bufseg */          \

"    push es"\

"    pop ds"\

\

"    xor dx, dx" /* literal continuation counter */ \

\

"    AGAIN:"\

\

     /* do I have any input? */ \

"    test bx, bx"\

"    jz KONIEC"\

"    dec bx"\

\

     /* load token */ \

"    lodsw"  /* mov ax, [ds:si] + inc si + inc si */ \

\

"    /* literal continuation? */"\

"    test dx, dx"\

"    jz TRY_BACKREF"\

"    stosw"\

"    dec dx" /* a byte shorter than dec dl */ \

"    jmp AGAIN"\

\

/* back ref? */ \

"    TRY_BACKREF:"\

"    test ax, 0xf000"\

"    jz LITERAL_START" /* else it's a literal start */ \

     /* AH = LLLL OOOO   AL = OOOO OOOO */ \

     /* copy (ah>>4)+1 bytes from (ax & 0x0FFF)+1 */ \

     /* save regs */ \

"    push si"\

     /* prep DS:SI = source ; ES:DI = destination ; CX = len */ \

"    mov ch, ah" /* this is all about setting CX to the high nibble of AX */ \

"    mov cl, 4"  /* using a code as compact as possible.                  */ \

"    shr ch, cl"\

"    mov cl, ch"\

"    xor ch, ch"\

"    inc cx"\

"    and ax, 0x0fff"  /* clear the backref length bits */ \

"    inc ax"\

"    mov si, di"\

"    sub si, ax"\

"    /* do the copy */"\

"    rep movsb" /* copy cx bytes from ds:si to es:di + inc si + inc di */ \

\

"    /* restore regs */"\

"    pop si"\

"    jmp AGAIN"\

\

"    LITERAL_START:" /* write al to dst and set literal counter */ \

     /* 0000 UUUU  BBBB BBBB */ \

"    stosb" /* mov [es:di], al + inc di */ \

"    mov dl, ah" /* ah high nibble is guaranteed to be zero */ \

"    jmp AGAIN"\

""\

"    KONIEC:"\

"    pop ds"\

modify [ax bx cx dx di si] \

parm [es] [di] [si] [bx]

#else

void mvucomp(char *dst, const unsigned short *src, unsigned short complen) {

  unsigned char rawwords = 0; /* number of uncompressible words */

  complen /= 2; /* I'm interested in number of words, not bytes */

  while (complen != 0) {

    unsigned short token;

    /* get next mvcomp token */

    token = *src;

    src++;

    complen--;

    /* token format is LLLL OOOO OOOO OOOO, where:

     * OOOO OOOO OOOO is the back reference offset (number of bytes-1 to rewind)

     * LLLL is the number of bytes (-1) that have to be copied from the offset.

     *

     * However, if LLLL is zero then the token's format is different:

     * 0000 RRRR BBBB BBBB

     *

     * The above form occurs when uncompressible data is encountered:

     * BBBB BBBB is the literal value of a byte to be copied

     * RRRR is the number of RAW (uncompressible) WORDS that follow (possibly 0)

     */

    /* raw word? */

    if (rawwords != 0) {

      unsigned short *dst16 = (void *)dst;

      *dst16 = token;

      dst += 2;

      rawwords--;

    /* literal byte? */

    } else if ((token & 0xF000) == 0) {

      *dst = token; /* no need for an explicit "& 0xff", dst is a char ptr so token is naturally truncated to lowest 8 bits */

      dst++;

      rawwords = token >> 8; /* number of RAW words that are about to follow */

    /* else it's a backreference */

    } else {

      char *src = dst - (token & 0x0FFF) - 1;

      token >>= 12;

      for (;;) {

        *dst = *src;

        dst++;

        src++;

        if (token == 0) break;

        token--;

      }

    }

  }

}

#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] & 0x7FFF) == langid) break; /* compare without highest bit - it is a flag for compression */

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

    FSEEK(fd, svarlang_string_count * 4);

    FSEEK(fd, buff16[1]);

  }

  /* load the index (dict) */

  if (FREAD(fd, svarlang_dict, svarlang_string_count * 4) != svarlang_string_count * 4) {

    exitcode = -4;

    goto FCLOSE_AND_EXIT;

  }

  /* is the lang block compressed? then uncompress it */

  if (buff16[0] & 0x8000) {

    unsigned short *mvcompptr;

    /* start by loading the entire block at the end of the svarlang mem */

    mvcompptr = (void *)(svarlang_mem + svarlang_memsz - buff16[1]);

    if (FREAD(fd, mvcompptr, buff16[1]) != buff16[1]) {

      exitcode = -5;

      goto FCLOSE_AND_EXIT;

    }

    /* uncompress now */

#ifndef MVUCOMP_ASM

    mvucomp(svarlang_mem, mvcompptr, buff16[1]);

#else

    mvucomp_asm(FP_SEG(svarlang_mem), FP_OFF(svarlang_mem), FP_OFF(svarlang_mem) + svarlang_memsz - buff16[1], buff16[1]);

#endif

    goto FCLOSE_AND_EXIT;

  }

  /* lang block not compressed - load as is */

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

    exitcode = -7;

  }

  FCLOSE_AND_EXIT:

  FCLOSE(fd);

  return(exitcode);

}