;=============================================================================
;				Crypt_02.asm
; This program will change the ciphertext in the file and output to another
; file!
;				Algorithm
; C1: Open the ciphertext file
; C2: Read the words into buffer
; C3: Output the buffer, with one space between words
; C4: Read a letter and check if it is Esc. If true => exit
; C5: Get what a letter must be changed to!
; C6: Save all
; C7: Change the specified letter in all the words
; C8: Show new => C3
;(C)I don't take any responsibility for the use of this program
;                           Zedr0n -- connection closed
;=============================================================================
;=============================================================================
; .Com declaration
;=============================================================================
.MODEL TINY			;
LOCALS @@
;=============================================================================
; Data definition/declaration
;=============================================================================
.DATA				;
;-----------------------------------------------------------------------------
; Equals
;-----------------------------------------------------------------------------
LENG EQU 	16	; Number of max letters in a word
LENGW EQU	50	; Max number of words in cipher text
;-----------------------------------------------------------------------------
; Structures
;-----------------------------------------------------------------------------
WORDS STRUC			;
	ELEM DB    	LENG DUP(?)
WORDS ENDS
;-----------------------------------------------------------------------------
; Constants
;-----------------------------------------------------------------------------
FILENAME DB	"CIPHER.TXT",0
CRLF     DB	0DH,0AH,'$'
;-----------------------------------------------------------------------------
; File variables
;-----------------------------------------------------------------------------
BUFFER WORDS LENGW DUP (?)	;
HFILE DW	?
;-----------------------------------------------------------------------------
; Stack variables
;-----------------------------------------------------------------------------


.CODE
.386
ORG 100H
;=============================================================================
; Code segment
;=============================================================================
START:				;
CUR_BYTE EQU [BP-1]
SOURCE   EQU [BP-2]		;
DEST     EQU [BP-3]

C1:				;
	ENTER 3,0
	MOV AH,3DH		;
	MOV DX,OFFSET FILENAME
        XOR AL,AL		; Read-only mode
	INT 21H			; 
	MOV HFILE,AX
	XOR BX,BX		;
	XOR DI,DI
C2:		
	CALL FIND_WORD		;
	MOV BX,DI
	PUSH BX
        CALL GET_WORD
	INC DI

	MOV AH,3FH
	MOV BX,HFILE		;
	MOV CX,1		;
	LEA DX,CUR_BYTE
	INT 21H			;
	MOV AH,CUR_BYTE
	CMP AH,'@'
	JNZ C2 
C3:				;

	CALL SHOW_BUFFER
C4:				;
	XOR AH,AH		;
	INT 16H			;
	CMP AH,1H		;
	JZ EXIT			;
	AND AL,5FH
	CMP AL,'A'
	JL C4			;
	CMP AL,'Z'		;
	JG C4			;
	MOV SOURCE,AL
C6:
	XOR AH,AH		;
	INT 16H
	CMP AH,1H		;
	JZ EXIT			;
	AND AL,5FH
	CMP AL,'A'		;
	JL C6			;
	CMP AL,'Z'		;
	JG C6
	MOV DEST,AL		;
C7:				;
	PUSH DEST		;
	PUSH SOURCE		;
	CALL CHANGE_SYM
	MOV AH,09H		;
	MOV DX,OFFSET CRLF	;
	INT 21H
	INT 21H			;
	INT 21H

	JMP C3
EXIT:
	LEAVE
        RET
;=============================================================================
; 				Procedures
;=============================================================================
INCLUDE ..\LIB\FILE.INC
;-----------------------------------------------------------------------------
; 				Get_Word
; Puts the word into the buffer with index specified by BX
;  				Algorithm
; G1: Get absolute index 
; G2: Get char, if not space, new line or non-letter =>  put into buffer
; G3: Exit
;
;
;-----------------------------------------------------------------------------
GET_WORD PROC			;
@@CUR_BYTE EQU	[BP-1]
	ENTER 1,0		;
	PUSHA
G1:				;
	IMUL BX,LENG 		;
	XOR DI,DI	

	MOV AH,3FH		;
	MOV CX,1		;
	LEA DX,@@CUR_BYTE
	PUSH BX
G2:				;
	POP BX			;
	PUSH BX
	MOV BX,HFILE
	MOV AH,3FH
	INT 21H			;
	MOV AH,@@CUR_BYTE	;
	CMP AH,20H		;
	JZ G3			;
 	CMP AH,0DH		;
	JZ G2			;
	CMP AH,0AH		;
	JZ G2
	CMP AH,'A'		;
	JL G2			;
	CMP AH,'Z'
	JG G2			;
	POP BX
	PUSH BX
	LEA BX,BUFFER[BX]
	MOV [BX][DI],AH		;
	INC DI
	JMP G2
G3:				;
	POP BX
	LEA BX,BUFFER[BX]	;
	MOV [BX][DI],'$'
	POPA
	LEAVE
	RET
GET_WORD ENDP
;-----------------------------------------------------------------------------
;				Show_buffer
; Outputs all the buffer with one space between words
; S1: Initialize counters
; S2: Show current word. Increase counter
; S3: Is it the last word? If not => S2
;-----------------------------------------------------------------------------
SHOW_BUFFER PROC		;
	PUSHA
S1:				;
 	PUSH -1
S2:		
	POP BX
	INC BX
	PUSH BX
	IMUL BX,16
	LEA DX,BUFFER[BX]
	MOV AH,09H		;
	INT 21H			;
	MOV DX,OFFSET CRLF	;
	INT 21H
S3:	
	DEC DI
 	JNZ S2
@@EXIT:
	POP BX
	POPA
	RET
SHOW_BUFFER ENDP
;-----------------------------------------------------------------------------
; 				Change_sym
; Change all the source chars to dest in the buffer
; H1: Initialize counters
; Ç2: Get word's offset
; H3: 
;-----------------------------------------------------------------------------
CHANGE_SYM PROC			;
@@DEST EQU [BP+6]		;
@@SOURCE EQU [BP+4]

	PUSH BP			;
	MOV BP,SP
	PUSHA
H1:				;
	PUSH -1  
H2:				;
	MOV DI,-1
	POP BX			;
	INC BX			;
	PUSH BX
 	CMP BX,SI		;
	JG @@EXIT
	IMUL BX,16		;
	LEA BX,BUFFER[BX]	;
	MOV AL,@@SOURCE
	MOV AH,@@DEST
H3:	
	INC DI
	CMP [BX+DI],'$'		;
	JZ H2
	CMP [BX+DI],AL
	JNZ H3			;
	MOV [BX+DI],AH
	JMP H3

@@EXIT:
	POP BX
	POPA			;
	POP BP
	RET
CHANGE_SYM ENDP

END START