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Amiga ACS 1998 #6
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texmap
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tmap_16.asm
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Assembly Source File
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1998-06-08
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7KB
|
250 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/tmap_16.asm $
; $Revision: 1.4 $
; $Author: mike $
; $Date: 1994/11/30 00:56:32 $
;
; 16 bits per pixel texture mapper
;
; $Log: tmap_16.asm $
; Revision 1.4 1994/11/30 00:56:32 mike
; optimization.
;
; Revision 1.3 1994/11/12 16:39:16 mike
; jae to ja.
;
; Revision 1.2 1993/11/22 10:23:49 mike
; *** empty log message ***
;
; Revision 1.1 1993/09/08 17:29:17 mike
; Initial revision
;
;
;
.386
public asm_tmap_scanline_lin_16_
include tmap_inc.asm
_DATA SEGMENT DWORD PUBLIC USE32 'DATA'
extrn _fx_u:dword
extrn _fx_v:dword
extrn _fx_du_dx:dword
extrn _fx_dv_dx:dword
extrn _fx_y:dword
extrn _fx_xleft:dword
extrn _fx_xright:dword
extrn _pixptr:dword
extrn _x:dword
extrn _loop_count:dword
_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
; _u fixed point initial u coordinate
; _v fixed point initial v coordinate
; _du_dx fixed point du/dx
; _dv_dx fixed point dv/dx
; 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);
;
; u += du_dx;
; v += dv_dx;
; z += dz_dx;
; }
align 4
asm_tmap_scanline_lin_16_:
pusha
; Setup for loop: _loop_count iterations = (int) xright - (int) xleft
; esi source pixel pointer = pixptr
; edi initial row pointer = y*320+x
; set esi = pointer to start of texture map data
mov esi,_pixptr
; set edi = address of first pixel to modify
mov edi,_fx_y
cmp edi,_window_bottom
ja _none_to_do
sub edi,_window_top
imul edi,_bytes_per_row
mov eax,_fx_xleft
sar eax,16
jns eax_ok
sub eax,eax
eax_ok:
sub eax,_window_left
add edi,eax
add edi,eax ; add again because it's 2 bytes/pixel
add edi,write_buffer
; set _loop_count = # of iterations
mov eax,_fx_xright
sar eax,16
cmp eax,_window_right
jb eax_ok1
mov eax,_window_right
eax_ok1: cmp eax,_window_left
ja eax_ok2
mov eax,_window_left
eax_ok2:
mov ebx,_fx_xleft
sar ebx,16
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
; edi destination pixel pointer
mov ebx,_fx_u
mov ecx,_fx_du_dx
mov edx,_fx_dv_dx
mov ebp,_fx_v
shl ebx,10
shl ebp,10
shl edx,10
shl ecx,10
; eax work
; ebx u
; ecx du_dx
; edx dv_dx
; ebp v
; esi read address
; edi write address
_size = (_end1 - _start1)/num_iters
mov eax,num_iters-1
sub eax,_loop_count
imul eax,eax,dword ptr _size
add eax,offset _start1
jmp eax
align 4
_start1:
; "OPTIMIZATIONS" maybe not worth making
; Getting rid of the esi from the mov al,[esi+eax] instruction.
; This would require moving into eax at the top of the loop, rather than doing the sub eax,eax.
; You would have to align your bitmaps so that the two shlds would create the proper base address.
; In other words, your bitmap data would have to begin at 4096x (for 64x64 bitmaps).
; I did timings without converting the sub to a mov eax,esi and setting esi to the proper value.
; There was a speedup of about 1% to 1.5% without converting the sub to a mov.
; Getting rid of the edi by doing a mov nnnn[edi],al instead of mov [edi],al.
; The problem with this is you would have a dword offset for nnnn. My timings indicate it is slower. (I think.)
; Combining u,v and du,dv into single longwords.
; The problem with this is you then must do a 16 bit operation to extract them, and you don't have enough
; instructions to separate a destination operand from being used by the next instruction. It shaves out one
; register instruction (an add reg,reg), but adds a 16 bit operation, and the setup is more complicated.
; usage:
; eax work
; ebx u coordinate
; ecx delta u
; edx delta v
; ebp v coordinate
; esi pointer to source bitmap
; edi write address
rept num_iters
mov eax,ebp ; clear for
add ebp,edx ; update v coordinate
shr eax,26 ; shift in v coordinate
shld eax,ebx,6 ; shift in u coordinate while shifting up v coordinate
add ebx,ecx ; update u coordinate
mov ax,[esi+2*eax] ; get pixel from source bitmap
mov [edi],ax
add edi,2
; inner loop if bitmaps are 256x256
; your register usage is bogus, and you must clear ecx
; fix your setup
; this is only about 10% faster in the inner loop
; this method would adapt to writing two pixels at a time better than
; the 64x64 method because you wouldn't run out of registers
; Note that this method assumes that both dv_dx and du_dx are in edx.
; edx = vi|vf|ui|uf
; where each field is 8 bits, vi = integer v coordinate, vf = fractional v coordinate, etc.
;** add ebx,edx
;** mov cl,bh
;** shld cx,bx,8
;** mov al,[esi+ecx]
;** mov [edi],al
;** inc edi
endm
_end1:
_none_to_do: popa
ret
_TEXT ends
end
; This is the inner loop to write two pixels at a time
; This is about 2.5% faster overall (on Mike's 66 MHz 80486 DX2, VLB)
; You must write code to even align edi and do half as many iterations, and write
; the beginning and ending extra pixels, if necessary.
; sub eax,eax ; clear for
; shld eax,ebp,6 ; shift in v coordinate
; add ebp,_fx_dv_dx ; update v coordinate
; shld eax,ebx,6 ; shift in u coordinate while shifting up v coordinate
; add ebx,ecx ; update u coordinate
; mov dl,[esi+eax] ; get pixel from source bitmap
;
; sub eax,eax ; clear for
; shld eax,ebp,6 ; shift in v coordinate
; add ebp,_fx_dv_dx ; update v coordinate
; shld eax,ebx,6 ; shift in u coordinate while shifting up v coordinate
; add ebx,ecx ; update u coordinate
; mov dh,[esi+eax] ; get pixel from source bitmap
;
; mov [edi],dx
; add edi,2