| 0,0 → 1,210 |
|---|
| /* |
| * a variety of helper functions |
| * Copyright (C) 2021 Mateusz Viste |
| */ |
| |
| #include <i86.h> /* MK_FP() */ |
| |
| #include "helpers.h" |
| |
| /* case-insensitive comparison of strings, returns non-zero on equality */ |
| int imatch(const char *s1, const char *s2) { |
| for (;;) { |
| char c1, c2; |
| c1 = *s1; |
| c2 = *s2; |
| if ((c1 >= 'a') && (c1 <= 'z')) c1 -= ('a' - 'A'); |
| if ((c2 >= 'a') && (c2 <= 'z')) c2 -= ('a' - 'A'); |
| /* */ |
| if (c1 != c2) return(0); |
| if (c1 == 0) return(1); |
| s1++; |
| s2++; |
| } |
| } |
| |
| |
| /* returns zero if s1 starts with s2 */ |
| int strstartswith(const char *s1, const char *s2) { |
| while (*s2 != 0) { |
| if (*s1 != *s2) return(-1); |
| s1++; |
| s2++; |
| } |
| return(0); |
| } |
| |
| |
| /* outputs a NULL-terminated string to stdout */ |
| void output_internal(const char *s, unsigned short nl) { |
| _asm { |
| mov ah, 0x02 /* AH=9 - write character in DL to stdout */ |
| mov si, s |
| cld /* clear DF so lodsb increments SI */ |
| NEXTBYTE: |
| lodsb /* load byte from DS:SI into AL, SI++ */ |
| mov dl, al |
| or al, 0 /* is al == 0? */ |
| jz DONE |
| int 0x21 |
| jmp NEXTBYTE |
| DONE: |
| or nl, 0 |
| jz FINITO |
| /* print out a CR/LF trailer if nl set */ |
| mov dl, 0x0D /* CR */ |
| int 0x21 |
| mov dl, 0x0A /* LF */ |
| int 0x21 |
| FINITO: |
| } |
| } |
| |
| |
| /* find first matching files using a FindFirst DOS call |
| * returns 0 on success or a DOS err code on failure */ |
| unsigned short findfirst(struct DTA *dta, const char *pattern, unsigned short attr) { |
| unsigned short res = 0; |
| _asm { |
| /* set DTA location */ |
| mov ah, 0x1a |
| mov dx, dta |
| int 0x21 |
| /* */ |
| mov ah, 0x4e /* FindFirst */ |
| mov dx, pattern |
| mov cx, attr |
| int 0x21 /* CF set on error + err code in AX, DTA filled with FileInfoRec on success */ |
| jnc DONE |
| mov [res], ax |
| DONE: |
| } |
| return(res); |
| } |
| |
| |
| /* find next matching, ie. continues an action intiated by findfirst() */ |
| unsigned short findnext(struct DTA *dta) { |
| unsigned short res = 0; |
| _asm { |
| mov ah, 0x4f /* FindNext */ |
| mov dx, dta |
| int 0x21 /* CF set on error + err code in AX, DTA filled with FileInfoRec on success */ |
| jnc DONE |
| mov [res], ax |
| DONE: |
| } |
| return(res); |
| } |
| |
| |
| /* print s string and wait for a single key press from stdin. accepts only |
| * key presses defined in the c ASCIIZ string. returns offset of pressed key |
| * in string. keys in c MUST BE UPPERCASE! */ |
| unsigned short askchoice(const char *s, const char *c) { |
| unsigned short res; |
| char key = 0; |
| |
| AGAIN: |
| output(s); |
| output(" "); |
| |
| _asm { |
| push ax |
| push dx |
| |
| mov ax, 0x0c01 /* clear input buffer and execute getchar (INT 21h,AH=1) */ |
| int 0x21 |
| /* if AL == 0 then this is an extended character */ |
| test al, al |
| jnz GOTCHAR |
| mov ah, 0x08 /* read again to flush extended char from input buffer */ |
| int 0x21 |
| xor al, al /* all extended chars are ignored */ |
| GOTCHAR: /* received key is in AL now */ |
| mov [key], al /* save key */ |
| |
| /* print a cr/lf */ |
| mov ah, 0x02 |
| mov dl, 0x0D |
| int 0x21 |
| mov dl, 0x0A |
| int 0x21 |
| |
| pop dx |
| pop ax |
| } |
| |
| /* ucase() result */ |
| if ((key >= 'a') && (key <= 'z')) key -= ('a' - 'A'); |
| |
| /* is there a match? */ |
| for (res = 0; c[res] != 0; res++) if (c[res] == key) return(res); |
| |
| goto AGAIN; |
| } |
| |
| |
| /* converts a path to its canonic representation */ |
| void file_truename(const char *src, char *dst) { |
| _asm { |
| mov ah, 0x60 /* query truename, DS:SI=src, ES:DI=dst */ |
| push ds |
| pop es |
| mov si, src |
| mov di, dst |
| int 0x21 |
| } |
| } |
| |
| |
| /* returns DOS attributes of file, or -1 on error */ |
| int file_getattr(const char *fname) { |
| int res = -1; |
| _asm { |
| mov ax, 0x4300 /* query file attributes, fname at DS:DX */ |
| mov dx, fname |
| int 0x21 /* CX=attributes if CF=0, otherwise AX=errno */ |
| jc DONE |
| mov [res], cx |
| DONE: |
| } |
| return(res); |
| } |
| |
| |
| /* returns screen's width (in columns) */ |
| unsigned short screen_getwidth(void) { |
| /* BIOS 0040:004A = word containing screen width in text columns */ |
| unsigned short far *scrw = MK_FP(0x40, 0x4a); |
| return(*scrw); |
| } |
| |
| |
| /* returns screen's height (in rows) */ |
| unsigned short screen_getheight(void) { |
| /* BIOS 0040:0084 = byte containing maximum valid row value (EGA ONLY) */ |
| unsigned char far *scrh = MK_FP(0x40, 0x84); |
| if (*scrh == 0) return(25); /* pre-EGA adapter */ |
| return(*scrh + 1); |
| } |
| |
| |
| /* displays the "Press any key to continue" msg and waits for a keypress */ |
| void press_any_key(void) { |
| output("Press any key to continue..."); |
| _asm { |
| mov ah, 0x08 /* no echo console input */ |
| int 0x21 /* pressed key in AL now (0 for extended keys) */ |
| test al, al |
| jnz DONE |
| int 0x21 /* executed ah=8 again to read the rest of extended key */ |
| DONE: |
| /* output CR/LF */ |
| mov ah, 0x02 |
| mov dl, 0x0D |
| int 0x21 |
| mov dl, 0x0A |
| int 0x21 |
| } |
| } |