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352 mateuszvis 1 
/*
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 * a variety of helper functions
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 * Copyright (C) 2021 Mateusz Viste
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 */
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#include "helpers.h"
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/* case-insensitive comparison of strings, returns non-zero on equality */
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int imatch(const char *s1, const char *s2) {
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  for (;;) {
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    char c1, c2;
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    c1 = *s1;
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    c2 = *s2;
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    if ((c1 >= 'a') && (c1 <= 'z')) c1 -= ('a' - 'A');
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    if ((c2 >= 'a') && (c2 <= 'z')) c2 -= ('a' - 'A');
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    /* */
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    if (c1 != c2) return(0);
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    if (c1 == 0) return(1);
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    s1++;
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    s2++;
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  }
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}
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/* returns zero if s1 starts with s2 */
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int strstartswith(const char *s1, const char *s2) {
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  while (*s2 != 0) {
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    if (*s1 != *s2) return(-1);
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    s1++;
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    s2++;
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  }
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  return(0);
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}
369 mateuszvis 34 
 
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/* outputs a NULL-terminated string to stdout */
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void output_internal(const char *s, unsigned short nl) {
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  _asm {
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    mov ah, 0x02 /* AH=9 - write character in DL to stdout */
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    mov si, s
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    cld          /* clear DF so lodsb increments SI */
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    NEXTBYTE:
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    lodsb /* load byte from DS:SI into AL, SI++ */
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    mov dl, al
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    or al, 0  /* is al == 0? */
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    jz DONE
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    int 0x21
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    jmp NEXTBYTE
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    DONE:
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    or nl, 0
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    jz FINITO
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    /* print out a CR/LF trailer if nl set */
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    mov dl, 0x0D /* CR */
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    int 0x21
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    mov dl, 0x0A /* LF */
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    int 0x21
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    FINITO:
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  }
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}
388 mateuszvis 60 
 
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/* find first matching files using a FindFirst DOS call
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 * returns 0 on success or a DOS err code on failure */
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unsigned short findfirst(struct DTA *dta, const char *pattern, unsigned short attr) {
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  unsigned short res = 0;
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  _asm {
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    /* set DTA location */
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    mov ah, 0x1a
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    mov dx, dta
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    int 0x21
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    /* */
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    mov ah, 0x4e    /* FindFirst */
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    mov dx, pattern
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    mov cx, attr
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    int 0x21        /* CF set on error + err code in AX, DTA filled with FileInfoRec on success */
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    jnc DONE
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    mov [res], ax
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    DONE:
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  }
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  return(res);
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}
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/* find next matching, ie. continues an action intiated by findfirst() */
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unsigned short findnext(struct DTA *dta) {
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  unsigned short res = 0;
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  _asm {
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    mov ah, 0x4f    /* FindNext */
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    mov dx, dta
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    int 0x21        /* CF set on error + err code in AX, DTA filled with FileInfoRec on success */
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    jnc DONE
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    mov [res], ax
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    DONE:
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  }
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  return(res);
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}