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405 mateuszvis 1 
/*
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 * echo
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 */
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static int cmd_echo(struct cmd_funcparam *p) {
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  unsigned short offs = FP_OFF(p->cmdline) + 5;
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  unsigned short segm = FP_SEG(p->cmdline);
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  unsigned char far *echostatus = MK_FP(p->rmod_seg, RMOD_OFFSET_ECHOFLAG);
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  /* display help only if /? is the only argument */
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  if ((p->argc == 1) && (imatch(p->argv[0], "/?"))) {
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    outputnl("Displays messages, or turns command-echoing on or off");
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    outputnl("");
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    outputnl("ECHO [ON | OFF]");
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    outputnl("ECHO [message]");
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    outputnl("");
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    outputnl("Type ECHO without parameters to display the current echo setting.");
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    return(-1);
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  }
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  /* ECHO without any parameter: display current state */
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  if (p->argc == 0) {
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    if (*echostatus) {
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      outputnl("ECHO is on");
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    } else {
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      outputnl("ECHO is off");
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    }
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    return(-1);
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  }
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  /* ECHO ON */
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  if ((p->argc == 1) && (imatch(p->argv[0], "on"))) {
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    *echostatus = 1;
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    return(-1);
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  }
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  /* ECHO OFF */
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  if ((p->argc == 1) && (imatch(p->argv[0], "off"))) {
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    *echostatus = 0;
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    return(-1);
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  }
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  /* ECHO MSG (start at cmdline+5 since first 5 are "ECHO" + separator) */
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  _asm {
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    push ax
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    push dx
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    push ds
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    push si
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    mov si, [offs]
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    cld           /* clear direction flag (DF) so lodsb increments SI */
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    mov ah, 0x02  /* display char from DL */
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    mov ds, [segm]
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    NEXTYBTE:
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    lodsb         /* load byte at DS:[SI] into AL and inc SI (if DF clear) */
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    or al, al     /* is AL == 0? then end of string reached */
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    jz DONE
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    mov dl, al
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    int 0x21
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    jmp NEXTYBTE
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    /* output a final CR/LF */
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    DONE:
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    mov dl, 0x0D
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    int 0x21
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    mov dl, 0x0A
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    int 0x21
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    pop si
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    pop ds
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    pop dx
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    pop ax
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  }
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  return(-1);
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}