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Amiga ACS 1998 #6
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amigaacscoverdisc1998-061998.iso
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descent
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texmap
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tmapfade.asm
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Assembly Source File
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1998-06-08
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4KB
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154 lines
;THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
;SOFTWARE CORPORATION ("PARALLAX"). PARALLAX, IN DISTRIBUTING THE CODE TO
;END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
;ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
;IN USING, DISPLAYING, AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
;SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
;FREE PURPOSES. IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
;CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES. THE END-USER UNDERSTANDS
;AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
;COPYRIGHT 1993-1998 PARALLAX SOFTWARE CORPORATION. ALL RIGHTS RESERVED.
;
; $Source: f:/miner/source/texmap/rcs/tmapfade.asm $
; $Revision: 1.6 $
; $Author: john $
; $Date: 1995/02/20 18:23:01 $
;
; .
;
; $Log: tmapfade.asm $
; Revision 1.6 1995/02/20 18:23:01 john
; Put all the externs in the assembly modules into tmap_inc.asm.
; Also, moved all the C versions of the inner loops into a new module,
; scanline.c.
;
; Revision 1.5 1995/02/20 17:09:15 john
; Added code so that you can build the tmapper with no assembly!
;
; Revision 1.4 1994/12/02 23:29:36 mike
; change jb/ja to jl/jg.
;
; Revision 1.3 1994/11/30 00:57:36 mike
; *** empty log message ***
;
; Revision 1.2 1994/10/06 18:38:49 john
; Added the ability to fade a scanline by calling gr_upoly_tmap
; with Gr_scanline_darkening_level with a value < MAX_FADE_LEVELS.
;
; Revision 1.1 1994/10/06 18:04:42 john
; Initial revision
;
;
.386
public asm_tmap_scanline_shaded_
include tmap_inc.asm
_DATA SEGMENT DWORD PUBLIC USE32 'DATA'
_loop_count dd 0
_DATA ENDS
DGROUP GROUP _DATA
_TEXT SEGMENT PARA PUBLIC USE32 'CODE'
ASSUME DS:_DATA
ASSUME CS:_TEXT
; --------------------------------------------------------------------------------------------------
; Enter:
; _xleft fixed point left x coordinate
; _xright fixed point right x coordinate
; _y fixed point y coordinate
;**; _pixptr address of source pixel map
; for (x = (int) xleft; x <= (int) xright; x++) {
; _setcolor(read_pixel_from_tmap(srcb,((int) (u/z)) & 63,((int) (v/z)) & 63));
; _setpixel(x,y);
;
; z += dz_dx;
; }
asm_tmap_scanline_shaded_:
push fs
pusha
mov fs, _gr_fade_table_selector
; Setup for loop: _loop_count iterations = (int) xright - (int) xleft
; edi initial row pointer = y*320+x
; set edi = address of first pixel to modify
mov edi,_fx_y
cmp edi,_window_bottom
jae _none_to_do
imul edi,_bytes_per_row
mov eax,_fx_xleft
test eax,eax
jns eax_ok
sub eax,eax
eax_ok:
add edi,eax
add edi,write_buffer
; set _loop_count = # of iterations
mov eax,_fx_xright
cmp eax,_window_right
jl eax_ok1
mov eax,_window_right
eax_ok1: cmp eax,_window_left
jg eax_ok2
mov eax,_window_left
eax_ok2:
mov ebx,_fx_xleft
sub eax,ebx
js _none_to_do
cmp eax,_window_width
jbe _ok_to_do
mov eax,_window_width
_ok_to_do:
mov _loop_count, eax
mov ecx, 0
mov ch,_tmap_flat_shade_value
and ch, 31
_size = (_end1 - _start1)/num_iters
mov eax,num_iters-1
sub eax,_loop_count
jns j_eax_ok1
inc eax ; sort of a hack, but we can get -1 here and want to be graceful
jns j_eax_ok1 ; if we jump, we had -1, which is kind of ok, if not, we int 3
int 3 ; oops, going to jump behind _start1, very bad...
sub eax,eax ; ok to continue
j_eax_ok1: imul eax,eax,dword ptr _size
add eax,offset _start1
jmp eax
align 4
_start1:
rept num_iters
local l1
mov cl, [edi] ; get pixel
mov al, fs:[ecx] ; darken pixel
mov [edi], al ; write pixel
inc edi ; goto next pixel
endm
_end1:
_none_to_do: popa
pop fs
ret
_TEXT ends
end