Keen: Modding

Code: Select all

%ext ck1
%version 1.31

################ Tuner Patch ###############
#-Alters a word variable in the code segment when the up/down arrows are pressed.
#-To alter something in another segment replace '$2E' in the base patch 
#-To invert up/down keys, swap $7F in the third row and $7C in the fourth row,
# and swap the min/maxvalues/deltas

#BASE PATCH - place this before CONSTANTS

#Skip diagonal-key checking                    
%patch $55EF $EB $4A          #jmp short 0x563B

#Disable vorticon border flash 
%patch $4A45 $C3  	

#tuning code
%patch $55F1 
$2E $A1 $00 $00 $8B $1E $CA $7F	 	
$D1 $E3	$2E $FF $A7 $00 $00	$3D
$00 $00 $7F $16 $05 $00 $00 $EB
$0D $3D $00 $00 $7C $0C $05 $00
$00 $EB $03 $B8 $00 $00 $2E $A3
$00 $00 $E9 $00 $00        

#jump table
%patch $4A48                     
$00 $56 $00 $56 $14 $56 $0A $56              
$0A $56 $0A $56 $14 $56 $00 $56 	         
$14 $56              

#CONSTANTS - Pick one block to tune a value in game (A jmp to $55F1 is required, they are included in these examples)

#1. Pogo Jetpack

%patch $55F3 $5B $3F       #VALUE_W (word in memory to be altered)
%patch $5619 $5B $3F	                      
%patch $55FE $48 $4A       #JUMPTABL_W (offset of jump table in code segment)
%patch $5601 $20 $00       #MAXVAL_W (maximum value; when up arrow pressed)
%patch $5606 $04 $00       #UPDELTA_W (rate of upwards change) 
%patch $560B $C0 $FF       #MINVAL_W (minimum value; when down arrow pressed)
%patch $5610 $FC $FF       #DOWNDELTA_W (rate of downward change)
%patch $5615 $F2 $FF       #DEFAULT_W (default vlaue; when no up or down pressed)
%patch $561C $32 $E9       #EXIT_W (jmp near at end of tuner patch)

#This is the jump to $55F1
%patch $3F49 $E9 $A5 $16 

##############################################

#2. Adjustable Raygun Angle

%patch $55F3 $EE $46        #VALUE_W
%patch $5619 $EE $46
%patch $55FE $48 $4A        #JUMPTABL_W
%patch $5601 $40 $00        #MAXVAL_W
%patch $5606 $40 $00        #UPDELTA_W
%patch $560B $C0 $FF        #MINVAL_W
%patch $5610 $C0 $FF        #DOWNDELTA_W
%patch $5615 $00 $00        #DEFAULT_W
%patch $561C $1D $00        #EXIT_W

#This constitutes the jump to $55F1
%patch $55EF $90 $90          

%end

Code: Select all

	// seg000:3F2D
	if (MEMW(word_1B01C) != 0 && (short)MEMW(keen_pos_y) < 0) {
		// seg000:3F3B
		PUSHI(0xffff);
		PUSHI(0xc8);
		EMU_CALL(a_pogo_jump, 3F46, think_30);
		reg_sp += 4;
	}

	// seg000:3F49
	if (MEMW(god_mode) != 0 && MEMW(word_1B01C) != 0) {
		// seg000:3F57
		W_MEMW(keen_pos_y, 0xff38);
	}