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/ Games of Daze / Infomagic - Games of Daze (Summer 1995) (Disc 1 of 2).iso / x2ftp / msdos / source / dakit / misca.asm < prev next >

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Assembly Source File | 1990-10-12 | 18.4 KB | 849 lines

;----------------------------------------------------------------- ; misca.asm ; --------- ; Miscellaneous minor assembly-language routines. ;----------------------------------------------------------------- include asm.inc include main.inc include ega.inc HEADER misca ;----------------------------------------------------------------- ; --- seg & offs of BIOS equipment flag word (we only use its lower byte) EQUIP_SEG equ 40h EQUIP_OFFS equ 10h DSEG ; --- Most recent i/o error code. NOTE: if there was not an error, ; this is undefined. public _ioError _ioError dw 0 ; --- used by shift_right public right_shift_masks right_shift_masks equ this word db 11111111b, 11111111b db 01111111b, 11111111b db 00111111b, 11111111b db 00011111b, 11111111b db 00001111b, 11111111b db 00000111b, 11111111b db 00000011b, 11111111b db 00000001b, 11111111b db 00000000b, 11111111b db 00000000b, 01111111b db 00000000b, 00111111b db 00000000b, 00011111b db 00000000b, 00001111b db 00000000b, 00000111b db 00000000b, 00000011b db 00000000b, 00000001b ; --- used by shift_left left_shift_masks equ this word db 11111111b, 11111111b db 11111111b, 11111110b db 11111111b, 11111100b db 11111111b, 11111000b db 11111111b, 11110000b db 11111111b, 11100000b db 11111111b, 11000000b db 11111111b, 10000000b db 11111111b, 00000000b db 11111110b, 00000000b db 11111100b, 00000000b db 11111000b, 00000000b db 11110000b, 00000000b db 11100000b, 00000000b db 11000000b, 00000000b db 10000000b, 00000000b ENDDS ;----------------------------------------------------------------- PSEG misca ;----------------------------------------------------------------- ; WORD dataseg (); ; Returns the current value of the DS register. ;----------------------------------------------------------------- public _dataseg STARTPROC _dataseg mov ax,ds ret ENDPROC _dataseg ;----------------------------------------------------------------- ; WORD codeseg (); ; Returns the current value of the CS register. ;----------------------------------------------------------------- public _codeseg STARTPROC _codeseg mov ax,cs ret ENDPROC _codeseg ;----------------------------------------------------------------- ; void far_setmem (seg, offs, length, value); ; WORD seg, offs; ; UWORD length; ; WORD value; ; Set length bytes starting at seg:offs to value. ; NOTE: This could be optimized by using stosw if possible. ;----------------------------------------------------------------- public _far_setmem STARTPROC _far_setmem push bp mov bp,sp push es push si push di mov es,ARGB[bp] ; segment mov di,ARGB+2[bp] ; offset mov cx,ARGB+4[bp] ; count mov al,ARGB+6[bp] ; value jcxz far_setmem_done cld rep stosb far_setmem_done: pop di pop si pop es pop bp ret ENDPROC _far_setmem ;----------------------------------------------------------------- ; void far_movmem (sseg, soffs, dseg, doffs, length); ; WORD sseg, soffs, dseg, doffs; ; UWORD length; ; Move length bytes starting at sseg:soffs to dseg:doffs. ; This proc doesn't handle overlapping source & dest. ; NOTE: Could speed this up by using WORD move! ;----------------------------------------------------------------- public _far_movmem STARTPROC _far_movmem push bp mov bp,sp push ds push es push si push di mov ds,ARGB[bp] ; source seg mov si,ARGB+2[bp] ; source offs mov es,ARGB+4[bp] ; dest seg mov di,ARGB+6[bp] ; dest offs mov0: mov cx,ARGB+8[bp] ; # bytes jcxz far_movmem_done move_left_to_right: cld rep movsb far_movmem_done: pop di pop si pop es pop ds pop bp ret ENDPROC _far_movmem ;----------------------------------------------------------------- ; void far_movmem_same_seg(UWORD seg, UWORD soffs, UWORD doffs, UWORD length); ; Move length bytes starting at seg:soffs to seg:doffs, ; dealing with possible OVERLAP -- ; when destination starts AFTER source, move RIGHT-TO-LEFT. ; NOTE: Could speed this up by using WORD move! ; NOTE: must have same register push/pop sequence as "_far_movmem". ;----------------------------------------------------------------- public _far_movmem_same_seg STARTPROC _far_movmem_same_seg push bp mov bp,sp push ds push es push si push di mov ds,ARGB[bp] ; source seg mov si,ARGB+2[bp] ; source offs mov es,ARGB[bp] ; dest seg mov di,ARGB+4[bp] ; dest offs mov cx,ARGB+6[bp] ; # bytes jcxz far_movmem_same_seg_done cmp di,si jbe move_left_to_right std ; Backwards through memory. add si,cx dec si ; Address of last byte. add di,cx dec di ; Address of last byte. rep movsb far_movmem_same_seg_done: cld pop di pop si pop es pop ds pop bp ret ENDPROC _far_movmem_same_seg ;----------------------------------------------------------------- ; void far_swapmem (sseg, soffs, dseg, doffs, length); ; WORD sseg, soffs, dseg, doffs; ; UWORD length; ; Swap length bytes starting at sseg:soffs with dseg:doffs. ; This proc doesn't handle overlapping source & dest. ; NOTE: Could speed this up by using WORD operations! (and by using xchg) ;----------------------------------------------------------------- public _far_swapmem STARTPROC _far_swapmem push bp mov bp,sp push ds push es push si push di mov ds,ARGB[bp] ; source seg mov si,ARGB+2[bp] ; source offs mov es,ARGB+4[bp] ; dest seg mov di,ARGB+6[bp] ; dest offs mov cx,ARGB+8[bp] ; # bytes jcxz far_swapmem_done cld swap_loop: mov al,[si] mov bl,es:[di] mov [si],bl mov es:[di],al inc si inc di loop swap_loop far_swapmem_done: pop di pop si pop es pop ds pop bp ret ENDPROC _far_swapmem ;----------------------------------------------------------------- ; LongFrac LFMULT (a, b); ; LongFrac a, b; ; Multiply two long fractions (ie, 32-bit fixed point numbers with 16 bits ; of binary fraction). ; ; register usage: ; [bp+ARGB] a.low ; [bp+ARGB+2] a.hi ; [bp+ARGB+4] b.lo ; [bp+ARGB+6] b.hi ; ax,dx = result (lo,hi) ;----------------------------------------------------------------- public _LFMULT STARTPROC _LFMULT push bp mov bp,sp push di push si xor si,si mov ax,[bp+ARGB+2] test ax,ax ; a>0 ? jns aplus not word ptr [bp+ARGB+2] ; a = -a neg word ptr [bp+ARGB] sbb word ptr [bp+ARGB+2],0ffffh not si aplus: mov ax,[bp+ARGB+6] test ax,ax ; b>0? jns bplus not word ptr [bp+ARGB+6] ; b = -b neg word ptr [bp+ARGB+4] sbb word ptr [bp+ARGB+6],0ffffh not si bplus: mov ax,[bp+ARGB] ; get a.lo mul word ptr [bp+ARGB+4] ; a.lo*b.lo mov bx,dx ; res.lo = highhalf(a.lo*b.lo) mov ax,[bp+ARGB+2] mul word ptr [bp+ARGB+6]; a.hi*b.hi mov cx,ax ; res.hi = lowhalf(a.hi*b.hi) mov ax,[bp+ARGB] mul word ptr [bp+ARGB+6] ; a.lo*b.hi add bx,ax adc cx,dx mov ax,[bp+ARGB+2] mul word ptr [bp+ARGB+4] ; a.hi*b.lo add ax,bx ; ax = lo adc dx,cx ; dx = hi test si,si jns leave ; if (neg) not dx ; res = -res neg ax sbb dx,0ffffh leave: pop si pop di pop bp ret ENDPROC _LFMULT ;----------------------------------------------------------------- ; Return TRUE if there is a char in the keyboard buffer, or FALSE otherwise. ;----------------------------------------------------------------- public _char_avail STARTPROC _char_avail mov ah,1 int 16h jz no_char_avail mov ax,-1 ret no_char_avail: xor ax,ax ret ENDPROC _char_avail ;----------------------------------------------------------------- ; Get an "extended" char, where normal chars are in the range 0-255, and ; non-ascii chars (for example, the function keys) are >= 256. ;----------------------------------------------------------------- public _get_char STARTPROC _get_char mov ah,0 int 16h or al,al jz gc_done xor ah,ah gc_done: ret ENDPROC _get_char ;----------------------------------------------------------------- ; set_ioError: if an io or critical error occurred, squirrels ; away the error code and clears did_crit_error and returns -1 ; ; Assumes that the carry flag and ax are the results of the last ; io operation (int 21h). ; ; If no error occurred, ax is unchanged. ;----------------------------------------------------------------- did_crit_error dw 0 ;NOTE: didn't include crit error handler in program. STARTPROC set_ioError pushf ; hold carry flag test cs:did_crit_error, 0ffffh jz noCritError push cs:did_crit_error pop _ioError popflags jmp short ioerr noCritError: popflags jnc iodone ; okay; leave ax unchanged mov _ioError,ax ioerr: mov cs:did_crit_error,0 mov ax,0ffffh ; return -1 for any error iodone: ret ENDPROC set_ioError ;----------------------------------------------------------------- ; Open Dos File: fileHandle = opendos (name, access); ;----------------------------------------------------------------- public _opendos STARTPROC _opendos push bp mov bp,sp mov al,[bp+ARGB+2] ; get access code mov dx,[bp+ARGB] ; pointer to name mov ah,03dh int 021h call set_ioError pop bp ret ENDPROC _opendos ;----------------------------------------------------------------- ; Create Dos File: fileHandle = creatdos (name); ;----------------------------------------------------------------- public _creatdos STARTPROC _creatdos push bp mov bp,sp xor cx,cx ; attribute= normal files mov dx,[bp+ARGB] ; pointer to name mov ah,03ch int 021h ; do open or create jnb cdx ; if carry flag is set mov ax,0FFFFh ; return -1 cdx: pop bp ret ENDPROC _creatdos ;----------------------------------------------------------------- ; Close Dos File: closedos (filehandle); ;----------------------------------------------------------------- public _closedos STARTPROC _closedos push bp mov bp,sp mov bx,[bp+ARGB] ; get file handle mov ah,03eh int 021h ; do read or write pop bp ret ENDPROC _closedos ;---------------------------------------------------------------------- ; Delete Dos File: deletedos (name); ;--------------------------------------------------------------------- public _deletedos STARTPROC _deletedos push bp mov bp,sp mov dx,ARGB[bp] ; pointer to name mov ah,41h int 21h ; delete file call set_ioError pop bp ret ENDPROC _deletedos ;----------------------------------------------------------------- ; Read from Dos File: nBytes = readdos (file, seg, offset, length); ;----------------------------------------------------------------- O_FILE = ARGB O_SEG = ARGB+2 O_OFFSET = ARGB+4 O_LENGTH = ARGB+6 public _readdos STARTPROC _readdos push bp mov bp,sp push ds mov ah,3fh mov bx,O_FILE[bp] mov cx,O_LENGTH[bp] mov ds,O_SEG[bp] mov dx,O_OFFSET[bp] int 021h call set_ioError pop ds pop bp ret ENDPROC _readdos ;----------------------------------------------------------------- ; Write to Dos File: nBytes = writedos (file, seg, offset, length); ; RETURN -1 on error. ;----------------------------------------------------------------- O_FILE = ARGB O_SEG = ARGB+2 O_OFFSET = ARGB+4 O_LENGTH = ARGB+6 public _writedos STARTPROC _writedos push bp mov bp,sp push ds mov ah,40h mov bx,O_FILE[bp] mov cx,O_LENGTH[bp] mov ds,O_SEG[bp] mov dx,O_OFFSET[bp] int 021h call set_ioError pop ds pop bp ret ENDPROC _writedos ;----------------------------------------------------------------- ; LFDIV (num, denom); ;----------------------------------------------------------------- NUM = ARGB DENOM = ARGB+4 public _LFDIV STARTPROC _LFDIV push bp mov bp,sp ; neg = FALSE xor cx,cx ; if (num < 0) { num = -num; neg = !neg; } cmp word ptr NUM+2[bp],0 jge lfdiv1 mov ax,NUM[bp] ; num = -num mov dx,NUM+2[bp] neg ax adc dx,0 neg dx mov NUM[bp],ax mov NUM+2[bp],dx not cx ; neg = !neg lfdiv1: ; if (denom < 0) { denom = -denom; neg = !neg; } cmp word ptr DENOM+2[bp],0 jge lfdiv2 mov ax,DENOM[bp] ; denom = -denom mov dx,DENOM+2[bp] neg ax adc dx,0 neg dx mov DENOM[bp],ax mov DENOM+2[bp],dx not cx ; neg = !neg lfdiv2: ; while (denom >= 0x10000) { num >>= 1; denom >>= 1; } mov bx,cx ; save neg in bx lfdiv5: mov cx,DENOM+2[bp] jcxz lfdiv3 sar word ptr NUM+2[bp],1 ; num >>= 1 rcr word ptr NUM[bp],1 sar word ptr DENOM+2[bp],1 ; denom >>= 1 rcr word ptr DENOM[bp],1 jmp lfdiv5 lfdiv3: mov cx,bx ; restore neg to cx ; high word of result = num / denom mov ax,NUM[bp] mov dx,NUM+2[bp] cmp dx,DENOM[bp] ; test for overflow jb no_overflow mov ax,7fffh ; overflow, so use a large # xor dx,dx jmp lfdiv6 no_overflow: div word ptr DENOM[bp] mov bx,ax ; low word of result = ((num % denom) << 16) / denom lfdiv6: xor ax,ax div word ptr DENOM[bp] mov dx,bx ; dx = high word of result ; if (neg) result = -result; jcxz lfdiv4 neg ax adc dx,0 neg dx lfdiv4: pop bp ret ENDPROC _LFDIV ;----------------------------------------------------------------- ; WORD get_first_mcb (); ; Returns address of first MCB in DOS free memory list. ;----------------------------------------------------------------- public _get_first_mcb STARTPROC _get_first_mcb mov ah,52h int 21h mov ax,es:[bx-2] ret ENDPROC _get_first_mcb ;----------------------------------------------------------------- ; WORD cdist (a, b); ; LONG a, b; ; Calculate the distance between RGB color values a and b. This is ; done using the sum of the absolute R,G,B deltas. It would be more ; accurate (but much slower) to calculate the actual distance between them. ; ; Improved: absdR + absdG + absdB + MAX(absdR, absdG, absdB). ; This approximates the sum of squares, by forcing large component to ; have double contribution to error term. ;----------------------------------------------------------------- A = ARGB B = ARGB+4 public _cdist STARTPROC _cdist push bp mov bp,sp ; --- clear top half of ax so we can use it as a word sub ah,ah ; --- get absolute distance between BLUE coords, put result in bx mov bl,A[bp] mov cl,B[bp] cmp bl,cl jae cdist_p1 xchg bl,cl cdist_p1: sub bl,cl sub bh,bh ; BX: abs(delta R). mov dx,bx ; dx will be MAX. ; --- get absolute distance between GREEN coords, add to bx mov al,A+1[bp] mov cl,B+1[bp] cmp al,cl jae cdist_p2 xchg al,cl cdist_p2: sub al,cl add bx,ax ; BX: absdR + absdG. cmp dx,ax jge cdist_R_ge_G mov dx,ax cdist_R_ge_G: ; DX: MAX(absdR, absdG). ; --- get absolute distance between RED coords, add bx to this value mov al,A+2[bp] mov cl,B+2[bp] cmp al,cl jae cdist_p3 xchg al,cl cdist_p3: sub al,cl add ax,bx ; AX: absdR + absdG + absdB. cmp dx,ax jge cdist_RG_ge_B mov dx,ax cdist_RG_ge_B: ; DX: MAX(absdR, absdG, absdB). add ax,dx ; AX: absdR + absdG + absdB + MAX(...). pop bp ret ENDPROC _cdist ;----------------------------------------------------------------- ; void dos_print_string (string); ; char *string; ; Call DOS to print the given string, in text mode. The string should ; not contain a '$', since DOS will treat that as the end of the string, ; and not print any chars after that! ;----------------------------------------------------------------- public _dos_print_string STARTPROC _dos_print_string push bp mov bp,sp push si ; --- replace the NULL terminator with a '$', like DOS wants mov si,ARGB[bp] dec si find_dollar: inc si mov al,[si] or al,al jnz find_dollar mov byte ptr [si],'$' ; --- call DOS to print the string push si mov ah,9 mov dx,ARGB[bp] int 21h pop si ; --- restore NULL string terminator mov byte ptr [si],0 pop si pop bp ret ENDPROC _dos_print_string ;----------------------------------------------------------------- ; Allocate Memory: segment = allocsome (paragraphs, &size) ; Will allocate request or largest remaining, whichever is bigger. ; Returns segment = 0 if failed. Puts number of paragraphs actually ; allocated into *size. ; Right now, this is only used by FixTandyMemory. ;----------------------------------------------------------------- public _allocsome STARTPROC _allocsome push bp mov bp,sp mov bx,[bp+ARGB] allocscont: mov di,[bp+ARGB+2] mov [di],bx ; return number of words allocated mov ax,0 cmp ax,bx je allocsret ; fail nothing requested mov ax,04800h int 021h ; execute DOS function jnc allocsret mov cx,ax mov ax,0 ; error: return NIL cmp cx,7 ; arena trashed jne allocscont ; keep trying until we alloc max left or fail allocsret: pop bp ret ENDPROC _allocsome ;----------------------------------------------------------------- ; LONG FreeDiskSpace (drive); ; WORD drive; /* 0 = drive A, 1 = drive B, etc... */ ; Returns free disk space in bytes on the specified drive. If there ; is an error accessing that drive, it returns 0. ;----------------------------------------------------------------- public _FreeDiskSpace STARTPROC _FreeDiskSpace push bp mov bp,sp mov ah,36h mov dl,ARGB[bp] inc dl ; this func uses 1 = drive A, 2 = drive B... int 21h cmp ax,0ffffh jne fds_no_error ; --- error getting info, so return 0 xor ax,ax xor dx,dx jmp fds_done ; --- no error, so return (sectorsPerCluster * bytesPerSector * freeClusters) ; NOTE: we assume that sectorsPerCluster * bytesPerSector < 64k. fds_no_error: mul cx mul bx fds_done: pop bp ret ENDPROC _FreeDiskSpace ;----------------------------------------------------------------- ; LONG GetSystemTime (); ; Returns the number of timer ticks (18.2 per second) since midnight. ;----------------------------------------------------------------- public _GetSystemTime STARTPROC _GetSystemTime mov ah,0 int 1ah mov ax,dx ; move low word to ax mov dx,cx ; move high word to dx ret ENDPROC _GetSystemTime ;----------------------------------------------------------------- ; name WordMulDiv -- ; ; c = (a*num)/denom; ; ; UWORD muldiv(a,num,denom) UWORD a,num,denom; ; ; register usage ; [bp+ARGB] a ; [bp+ARGB+2] num ; [bp+ARGB+4] denom ;----------------------------------------------------------------- public _WordMulDiv STARTPROC _WordMulDiv push bp mov bp,sp mov ax,[bp+ARGB] mul word ptr[bp+ARGB+2] div word ptr[bp+ARGB+4] pop bp ret ENDPROC _WordMulDiv ;----------------------------------------------------------------- ENDPS misca END