�>>> Environment Mapping
9�    Alain BROBECKER (baah/Arm's Tech) on 05-Apr-1998

(O�==== ASM CODE ============================================================
2.�code% 1024:�opt%=0�2�2:P%=code%:[opt opt%
<R.old_stack              ; Used to save r13, will overwrite on 'envmap' routine
F
P ;\\\\\\\\\\\\\\\\\\\\\\\\\\\
Z!; Calculate Environment Map >
d ;///////////////////////////
nO;This routine creates the environment map. We calculate the intensity as an
x4;affine function of the distance d=SQR(x^2+y^2).
�?;           r0=adress where to save 128*128 environment map
�.envmap
�   stmfd     r13!,{r0-r5,r14}
�1  mov       r1,#256                 ; y coord
�
.env_y
�1  mov       r2,#256                 ; x coord
�2  sub       r4,r1,#128              ; r5=y-128
�6  mul       r3,r4,r4                ; r4=(y-128)^2
�
.env_x
�3  sub       r14,r2,#128             ; r14=x-128
�@  mla       r5,r14,r14,r3           ; r6=(x-128)^2+(y-128)^2
�E  �sqrt(4,5,14)                    ; r5=sqrt((x-128)^2+(y-128)^2)
�  mov       r4,r4,lsl #1

<  rsbS      r4,r4,#255              ; r5=255-2*sqrt(...)

  movMI     r4,#0

4  strB      r4,[r0],#1              ; Save pixel

"4 subS r2,r2,#1:bNE env_x            ; Next pixel

,3 subS r1,r1,#1:bNE env_y            ; Next line

6   ldmfd     r13!,{r0-r5,pc}^

@

J!;\\\\\\\\\\\\\\\\\\\\\\\\\\\\

T"; Compute Displacements Table>

^!;////////////////////////////

hN;This routine use the height field image to create the displacement table.

rQ;Formulaes are disp_x(x;y)=h(x+1;y)-h(x-1;y) & disp_y(x;y)=h(x;y+1)-h(x;y-1).

|$;           r0=adress of heights

�:;           r1=table which will contain disp_x, disp_y

�.displacements

�   stmfd     r13!,{r0-r5,r14}

�/  mov       r2,#0                   ; y<<24

�.disp_y

�/  mov       r3,#0                   ; x<<24

�.disp_x

�3  add       r5,r0,r2,lsr #16        ; r5=h(0;y)

�>  sub       r4,r3,#1<<24            ; r4=(x-1 mod 255)<<24

�5  ldrB      r4,[r5,r4,lsr #24]      ; r4=h(x-1;y)

�?  add       r14,r3,#1<<24           ; r14=(x+1 mod 255)<<24

�6  ldrB      r14,[r5,r14,lsr #24]    ; r14=h(x+1;y)

�>  sub       r4,r14,r4               ; r4=h(x+1;y)-h(x-1;y)
  mov       r4,r4,asr #1
  add       r4,r4,#128
  strB      r4,[r1],#1
&3  add       r5,r0,r3,lsr #24        ; r5=h(x;0)
0>  sub       r4,r2,#1<<24            ; r4=(y-1 mod 255)<<24
:5  ldrB      r4,[r5,r4,lsr #16]      ; r4=h(x;y-1)
D?  add       r14,r2,#1<<24           ; r14=(y+1 mod 255)<<24
N6  ldrB      r14,[r5,r14,lsr #16]    ; r14=h(x;y+1)
X>  sub       r4,r14,r4               ; r4=h(x;y+1)-h(x;y-1)
b  mov       r4,r4,asr #1
l  add       r4,r4,#128
v  strB      r4,[r1],#1
�M addS r3,r3,#1<<24:bNE disp_x       ; x=(x+1 mod255)<<24, continue if <>0
�M addS r2,r2,#1<<24:bNE disp_x       ; y=(y+1 mod255)<<24, continue if <>0
�   ldmfd     r13!,{r0-r5,pc}^
�
�;\\\\\\\\\\\\\\\\\\\\\\\\\\
� ; Draw Environment Mapping >
�;//////////////////////////
�O;For each screen pixel we compute which pixel to copy from environment map.
�F;Formula is screen(x;y)=envmap(disp_x(x;y)+lx-x;disp_y(x;y)+ly-y).
�;           r0=vram
�,;           r1=table with disp_x, disp_y
�4;           r2=adress of 256*256 environment map
�;           r3=lx
;           r4=ly

.draw_env
!  stmfd     r13!,{r0-r12,r14}
   str       r13,old_stack
*2  mov       r5,#0                   ; r5=y<<24
4.draw_y
>2  mov       r6,#0                   ; r6=x<<24
H2  sub       r11,r4,r5,lsr #24       ; r11=ly-y
R.draw_x4
\2  sub       r12,r3,r6,lsr #24       ; r12=lx-x
f@  ldmia     r1!,{r13,r14}           ; Load 4*2 displacements
p?  mov       r9,#0                   ; Will contain 4 points
z3  and       r7,r13,#&ff             ; r7=disp_x
�6  and       r8,r13,#&ff00           ; r8=disp_y<<8
�;  addS      r7,r7,r12               ; r7=dx=disp_x+lx-x
�C  addGES    r8,r8,r11,lsl #8        ; r8=dy<<8=(disp_y+ly-y)<<8
�D  bMI       draw_next1              ; Don't draw if dx<0 or dy<0
�  cmp       r7,#&ff
�  cmpLE     r8,#&ff00
�K  addLE     r8,r7,r8                ; If dx<256 and dy<256, r8=dy<<8+dx
�E  ldrLEB    r9,[r2,r8]              ; And put envmap(dx;dy) in r9
�.draw_next1
�;  sub       r12,r12,#1              ; lx-x-=1 (ie x+=1)
�<  and       r7,r13,#&ff0000         ; Similar, 2nd pixel
�!  addS      r7,r7,r12,lsl #16
�"  addGES    r8,r11,r13,lsr #24
  bMI       draw_next2
  cmp       r7,#&ff0000
  cmpLE     r8,#&ff
$"  addLE     r8,r7,r8,lsl #24  
."  ldrLEB    r8,[r2,r8,lsr #16]
8  addLE     r9,r9,r8,lsl #8
B.draw_next2
L  sub       r12,r12,#1
V3  and       r7,r14,#&ff             ; 3rd pixel
`  and       r8,r14,#&ff00
j  addS      r7,r7,r12
t   addGES    r8,r8,r11,lsl #8
~  bMI       draw_next3
�  cmp       r7,#&ff
�  cmpLE     r8,#&ff00
�  addLE     r8,r7,r8
�  ldrLEB    r8,[r2,r8]
�   addLE     r9,r9,r8,lsl #16
�.draw_next3
�  sub       r12,r12,#1
�3  and       r7,r14,#&ff0000         ; 4th pixel
�!  addS      r7,r7,r12,lsl #16
�"  addGES    r8,r11,r14,lsr #24
�  bMI       draw_next4
�  cmp       r7,#&ff0000
  cmpLE     r8,#&ff

   addLE     r8,r7,r8,lsl #24
"  ldrLEB    r8,[r2,r8,lsr #16]
   addLE     r9,r9,r8,lsl #24
(.draw_next4
27  str       r9,[r0],#4              ; Save 4 pixels
<C addS r6,r6,#4<<24:bNE draw_x4      ; x+=4<<24, continue if <>0
F8  add       r0,r0,#320-256          ; Next vram line
PC addS r5,r5,#1<<24:bNE draw_y       ; y+=1<<24, continue if <>0
Z  ldr       r13,old_stack
d!  ldmfd     r13!,{r0-r12,pc}^
n  
x.screenmode
�
  dcd   1
�  dcd   320
�  dcd   256
�
  dcd   3
�  dcd   -1
�  dcd   0:dcd 128
�  dcd   3:dcd 255
�  dcd   -1
�  
�7]:�opt%:�"Assembly code is ";P%-code%;" bytes long"
�
�O�==== BASIC CODE ==========================================================
��envmap% 65536
��disp% 65536*2
0�Load height field and compute displacements
�"Computing displacements" 
A%=envmap%:B%=disp%
"4f%=�("Height256"):ș"OS_GBPB",4,f%,A%,65536:�#f%
,�displacements
6�Create environment map
@ �"Computing environment map"
JA%=envmap%:�envmap
T
^<�Screen & color initialisation. Then let the show begin.
h(�15:ș"OS_ScreenMode",0,screenmode:�
r>�v% 8:!v%=148:v%!4=-1:ș"OS_ReadVduVariables",v%,v%:v%=!v%
s
�c%=1�255
t w%=255*(c%/255)^1.2
u g%=w%*w%/255
v r%=�w%*15
w b%=w%*�(-w%*w%/500)
� �c%,r%,g%,b%
��c%
�b%=2
�B%=disp%
�C%=envmap%
��
�5 Ȗ:ș"OS_Byte",&71,b%:b%=b%�3:ș"OS_Byte",&70,b%
� A%=v%+(b%>>1)*81920+32
� ȗx%,y%,z%
�! D%=(x%>>1)-32:E%=256-(y%>>1)
� �draw_env
���

E�==== MACROS ====================================================
�m0=sqrt(m1).
&ݤsqrt(m0,m1,m2)
0�n%
:
[opt opt%
DG  mov       m0,#0                   ; This is ripped from Jan/BASS.
N,  mov       m2,#1<<30               ;  |
X,  cmp       m1,m2                   ;  |
b,  subHS     m1,m0,m2                ;  |
l,  adc       m0,m0,m0                ;  |
v]:�n%=2�30�2:[opt opt%
�,  add       m2,m0,#1<<30            ;  |
�,  cmp       m1,m2,ror #n%           ;  |
�,  subHS     m1,m1,m2,ror #n%        ;  |
�=  adc       m0,m0,m0                ; End of ripped code.
�]:�n%:[opt opt%
�9  cmp       m1,m0                   ; Flags=val-root.
�C  addPL     m0,m0,#1                ; Round to nearest integer.
�	]:=""
�

00000000  0d 00 0a 1c f4 3e 3e 3e  20 45 6e 76 69 72 6f 6e  |.....>>> Environ|
00000010  6d 65 6e 74 20 4d 61 70  70 69 6e 67 0d 00 14 39  |ment Mapping...9|
00000020  f4 20 20 20 20 41 6c 61  69 6e 20 42 52 4f 42 45  |.    Alain BROBE|
00000030  43 4b 45 52 20 28 62 61  61 68 2f 41 72 6d 27 73  |CKER (baah/Arm's|
00000040  20 54 65 63 68 29 20 6f  6e 20 30 35 2d 41 70 72  | Tech) on 05-Apr|
00000050  2d 31 39 39 38 0d 00 1e  04 0d 00 28 4f f4 3d 3d  |-1998......(O.==|
00000060  3d 3d 20 41 53 4d 20 43  4f 44 45 20 3d 3d 3d 3d  |== ASM CODE ====|
00000070  3d 3d 3d 3d 3d 3d 3d 3d  3d 3d 3d 3d 3d 3d 3d 3d  |================|
*
000000a0  3d 3d 3d 3d 3d 3d 3d 3d  0d 00 32 2e de 63 6f 64  |========..2..cod|
000000b0  65 25 20 31 30 32 34 3a  e3 6f 70 74 25 3d 30 b8  |e% 1024:.opt%=0.|
000000c0  32 88 32 3a 50 25 3d 63  6f 64 65 25 3a 5b 6f 70  |2.2:P%=code%:[op|
000000d0  74 20 6f 70 74 25 0d 00  3c 52 2e 6f 6c 64 5f 73  |t opt%..<R.old_s|
000000e0  74 61 63 6b 20 20 20 20  20 20 20 20 20 20 20 20  |tack            |
000000f0  20 20 3b 20 55 73 65 64  20 74 6f 20 73 61 76 65  |  ; Used to save|
00000100  20 72 31 33 2c 20 77 69  6c 6c 20 6f 76 65 72 77  | r13, will overw|
00000110  72 69 74 65 20 6f 6e 20  27 65 6e 76 6d 61 70 27  |rite on 'envmap'|
00000120  20 72 6f 75 74 69 6e 65  0d 00 46 04 0d 00 50 20  | routine..F...P |
00000130  3b 5c 5c 5c 5c 5c 5c 5c  5c 5c 5c 5c 5c 5c 5c 5c  |;\\\\\\\\\\\\\\\|
00000140  5c 5c 5c 5c 5c 5c 5c 5c  5c 5c 5c 5c 0d 00 5a 21  |\\\\\\\\\\\\..Z!|
00000150  3b 20 43 61 6c 63 75 6c  61 74 65 20 45 6e 76 69  |; Calculate Envi|
00000160  72 6f 6e 6d 65 6e 74 20  4d 61 70 20 3e 0d 00 64  |ronment Map >..d|
00000170  20 3b 2f 2f 2f 2f 2f 2f  2f 2f 2f 2f 2f 2f 2f 2f  | ;//////////////|
00000180  2f 2f 2f 2f 2f 2f 2f 2f  2f 2f 2f 2f 2f 0d 00 6e  |/////////////..n|
00000190  4f 3b 54 68 69 73 20 72  6f 75 74 69 6e 65 20 63  |O;This routine c|
000001a0  72 65 61 74 65 73 20 74  68 65 20 65 6e 76 69 72  |reates the envir|
000001b0  6f 6e 6d 65 6e 74 20 6d  61 70 2e 20 57 65 20 63  |onment map. We c|
000001c0  61 6c 63 75 6c 61 74 65  20 74 68 65 20 69 6e 74  |alculate the int|
000001d0  65 6e 73 69 74 79 20 61  73 20 61 6e 0d 00 78 34  |ensity as an..x4|
000001e0  3b 61 66 66 69 6e 65 20  66 75 6e 63 74 69 6f 6e  |;affine function|
000001f0  20 6f 66 20 74 68 65 20  64 69 73 74 61 6e 63 65  | of the distance|
00000200  20 64 3d 53 51 52 28 78  5e 32 2b 79 5e 32 29 2e  | d=SQR(x^2+y^2).|
00000210  0d 00 82 3f 3b 20 20 20  20 20 20 20 20 20 20 20  |...?;           |
00000220  72 30 3d 61 64 72 65 73  73 20 77 68 65 72 65 20  |r0=adress where |
00000230  74 6f 20 73 61 76 65 20  31 32 38 2a 31 32 38 20  |to save 128*128 |
00000240  65 6e 76 69 72 6f 6e 6d  65 6e 74 20 6d 61 70 0d  |environment map.|
00000250  00 8c 0b 2e 65 6e 76 6d  61 70 0d 00 96 20 20 20  |....envmap...   |
00000260  73 74 6d 66 64 20 20 20  20 20 72 31 33 21 2c 7b  |stmfd     r13!,{|
00000270  72 30 2d 72 35 2c 72 31  34 7d 0d 00 a0 31 20 20  |r0-r5,r14}...1  |
00000280  6d 6f 76 20 20 20 20 20  20 20 72 31 2c 23 32 35  |mov       r1,#25|
00000290  36 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |6               |
000002a0  20 20 3b 20 79 20 63 6f  6f 72 64 0d 00 aa 0a 2e  |  ; y coord.....|
000002b0  65 6e 76 5f 79 0d 00 b4  31 20 20 6d 6f 76 20 20  |env_y...1  mov  |
000002c0  20 20 20 20 20 72 32 2c  23 32 35 36 20 20 20 20  |     r2,#256    |
000002d0  20 20 20 20 20 20 20 20  20 20 20 20 20 3b 20 78  |             ; x|
000002e0  20 63 6f 6f 72 64 0d 00  be 32 20 20 73 75 62 20  | coord...2  sub |
000002f0  20 20 20 20 20 20 72 34  2c 72 31 2c 23 31 32 38  |      r4,r1,#128|
00000300  20 20 20 20 20 20 20 20  20 20 20 20 20 20 3b 20  |              ; |
00000310  72 35 3d 79 2d 31 32 38  0d 00 c8 36 20 20 6d 75  |r5=y-128...6  mu|
00000320  6c 20 20 20 20 20 20 20  72 33 2c 72 34 2c 72 34  |l       r3,r4,r4|
00000330  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000340  3b 20 72 34 3d 28 79 2d  31 32 38 29 5e 32 0d 00  |; r4=(y-128)^2..|
00000350  d2 0a 2e 65 6e 76 5f 78  0d 00 dc 33 20 20 73 75  |...env_x...3  su|
00000360  62 20 20 20 20 20 20 20  72 31 34 2c 72 32 2c 23  |b       r14,r2,#|
00000370  31 32 38 20 20 20 20 20  20 20 20 20 20 20 20 20  |128             |
00000380  3b 20 72 31 34 3d 78 2d  31 32 38 0d 00 e6 40 20  |; r14=x-128...@ |
00000390  20 6d 6c 61 20 20 20 20  20 20 20 72 35 2c 72 31  | mla       r5,r1|
000003a0  34 2c 72 31 34 2c 72 33  20 20 20 20 20 20 20 20  |4,r14,r3        |
000003b0  20 20 20 3b 20 72 36 3d  28 78 2d 31 32 38 29 5e  |   ; r6=(x-128)^|
000003c0  32 2b 28 79 2d 31 32 38  29 5e 32 0d 00 f0 45 20  |2+(y-128)^2...E |
000003d0  20 a4 73 71 72 74 28 34  2c 35 2c 31 34 29 20 20  | .sqrt(4,5,14)  |
000003e0  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
000003f0  20 20 3b 20 72 35 3d 73  71 72 74 28 28 78 2d 31  |  ; r5=sqrt((x-1|
00000400  32 38 29 5e 32 2b 28 79  2d 31 32 38 29 5e 32 29  |28)^2+(y-128)^2)|
00000410  0d 00 fa 1c 20 20 6d 6f  76 20 20 20 20 20 20 20  |....  mov       |
00000420  72 34 2c 72 34 2c 6c 73  6c 20 23 31 0d 01 04 3c  |r4,r4,lsl #1...<|
00000430  20 20 72 73 62 53 20 20  20 20 20 20 72 34 2c 72  |  rsbS      r4,r|
00000440  34 2c 23 32 35 35 20 20  20 20 20 20 20 20 20 20  |4,#255          |
00000450  20 20 20 20 3b 20 72 35  3d 32 35 35 2d 32 2a 73  |    ; r5=255-2*s|
00000460  71 72 74 28 2e 2e 2e 29  0d 01 0e 15 20 20 6d 6f  |qrt(...)....  mo|
00000470  76 4d 49 20 20 20 20 20  72 34 2c 23 30 0d 01 18  |vMI     r4,#0...|
00000480  34 20 20 73 74 72 42 20  20 20 20 20 20 72 34 2c  |4  strB      r4,|
00000490  5b 72 30 5d 2c 23 31 20  20 20 20 20 20 20 20 20  |[r0],#1         |
000004a0  20 20 20 20 20 3b 20 53  61 76 65 20 70 69 78 65  |     ; Save pixe|
000004b0  6c 0d 01 22 34 20 73 75  62 53 20 72 32 2c 72 32  |l.."4 subS r2,r2|
000004c0  2c 23 31 3a 62 4e 45 20  65 6e 76 5f 78 20 20 20  |,#1:bNE env_x   |
000004d0  20 20 20 20 20 20 20 20  20 3b 20 4e 65 78 74 20  |         ; Next |
000004e0  70 69 78 65 6c 0d 01 2c  33 20 73 75 62 53 20 72  |pixel..,3 subS r|
000004f0  31 2c 72 31 2c 23 31 3a  62 4e 45 20 65 6e 76 5f  |1,r1,#1:bNE env_|
00000500  79 20 20 20 20 20 20 20  20 20 20 20 20 3b 20 4e  |y            ; N|
00000510  65 78 74 20 6c 69 6e 65  0d 01 36 20 20 20 6c 64  |ext line..6   ld|
00000520  6d 66 64 20 20 20 20 20  72 31 33 21 2c 7b 72 30  |mfd     r13!,{r0|
00000530  2d 72 35 2c 70 63 7d 5e  0d 01 40 04 0d 01 4a 21  |-r5,pc}^..@...J!|
00000540  3b 5c 5c 5c 5c 5c 5c 5c  5c 5c 5c 5c 5c 5c 5c 5c  |;\\\\\\\\\\\\\\\|
00000550  5c 5c 5c 5c 5c 5c 5c 5c  5c 5c 5c 5c 5c 0d 01 54  |\\\\\\\\\\\\\..T|
00000560  22 3b 20 43 6f 6d 70 75  74 65 20 44 69 73 70 6c  |"; Compute Displ|
00000570  61 63 65 6d 65 6e 74 73  20 54 61 62 6c 65 3e 0d  |acements Table>.|
00000580  01 5e 21 3b 2f 2f 2f 2f  2f 2f 2f 2f 2f 2f 2f 2f  |.^!;////////////|
00000590  2f 2f 2f 2f 2f 2f 2f 2f  2f 2f 2f 2f 2f 2f 2f 2f  |////////////////|
000005a0  0d 01 68 4e 3b 54 68 69  73 20 72 6f 75 74 69 6e  |..hN;This routin|
000005b0  65 20 75 73 65 20 74 68  65 20 68 65 69 67 68 74  |e use the height|
000005c0  20 66 69 65 6c 64 20 69  6d 61 67 65 20 74 6f 20  | field image to |
000005d0  63 72 65 61 74 65 20 74  68 65 20 64 69 73 70 6c  |create the displ|
000005e0  61 63 65 6d 65 6e 74 20  74 61 62 6c 65 2e 0d 01  |acement table...|
000005f0  72 51 3b 46 6f 72 6d 75  6c 61 65 73 20 61 72 65  |rQ;Formulaes are|
00000600  20 64 69 73 70 5f 78 28  78 3b 79 29 3d 68 28 78  | disp_x(x;y)=h(x|
00000610  2b 31 3b 79 29 2d 68 28  78 2d 31 3b 79 29 20 26  |+1;y)-h(x-1;y) &|
00000620  20 64 69 73 70 5f 79 28  78 3b 79 29 3d 68 28 78  | disp_y(x;y)=h(x|
00000630  3b 79 2b 31 29 2d 68 28  78 3b 79 2d 31 29 2e 0d  |;y+1)-h(x;y-1)..|
00000640  01 7c 24 3b 20 20 20 20  20 20 20 20 20 20 20 72  |.|$;           r|
00000650  30 3d 61 64 72 65 73 73  20 6f 66 20 68 65 69 67  |0=adress of heig|
00000660  68 74 73 0d 01 86 3a 3b  20 20 20 20 20 20 20 20  |hts...:;        |
00000670  20 20 20 72 31 3d 74 61  62 6c 65 20 77 68 69 63  |   r1=table whic|
00000680  68 20 77 69 6c 6c 20 63  6f 6e 74 61 69 6e 20 64  |h will contain d|
00000690  69 73 70 5f 78 2c 20 64  69 73 70 5f 79 0d 01 90  |isp_x, disp_y...|
000006a0  12 2e 64 69 73 70 6c 61  63 65 6d 65 6e 74 73 0d  |..displacements.|
000006b0  01 9a 20 20 20 73 74 6d  66 64 20 20 20 20 20 72  |..   stmfd     r|
000006c0  31 33 21 2c 7b 72 30 2d  72 35 2c 72 31 34 7d 0d  |13!,{r0-r5,r14}.|
000006d0  01 a4 2f 20 20 6d 6f 76  20 20 20 20 20 20 20 72  |../  mov       r|
000006e0  32 2c 23 30 20 20 20 20  20 20 20 20 20 20 20 20  |2,#0            |
000006f0  20 20 20 20 20 20 20 3b  20 79 3c 3c 32 34 0d 01  |       ; y<<24..|
00000700  ae 0b 2e 64 69 73 70 5f  79 0d 01 b8 2f 20 20 6d  |...disp_y.../  m|
00000710  6f 76 20 20 20 20 20 20  20 72 33 2c 23 30 20 20  |ov       r3,#0  |
00000720  20 20 20 20 20 20 20 20  20 20 20 20 20 20 20 20  |                |
00000730  20 3b 20 78 3c 3c 32 34  0d 01 c2 0b 2e 64 69 73  | ; x<<24.....dis|
00000740  70 5f 78 0d 01 cc 33 20  20 61 64 64 20 20 20 20  |p_x...3  add    |
00000750  20 20 20 72 35 2c 72 30  2c 72 32 2c 6c 73 72 20  |   r5,r0,r2,lsr |
00000760  23 31 36 20 20 20 20 20  20 20 20 3b 20 72 35 3d  |#16        ; r5=|
00000770  68 28 30 3b 79 29 0d 01  d6 3e 20 20 73 75 62 20  |h(0;y)...>  sub |
00000780  20 20 20 20 20 20 72 34  2c 72 33 2c 23 31 3c 3c  |      r4,r3,#1<<|
00000790  32 34 20 20 20 20 20 20  20 20 20 20 20 20 3b 20  |24            ; |
000007a0  72 34 3d 28 78 2d 31 20  6d 6f 64 20 32 35 35 29  |r4=(x-1 mod 255)|
000007b0  3c 3c 32 34 0d 01 e0 35  20 20 6c 64 72 42 20 20  |<<24...5  ldrB  |
000007c0  20 20 20 20 72 34 2c 5b  72 35 2c 72 34 2c 6c 73  |    r4,[r5,r4,ls|
000007d0  72 20 23 32 34 5d 20 20  20 20 20 20 3b 20 72 34  |r #24]      ; r4|
000007e0  3d 68 28 78 2d 31 3b 79  29 0d 01 ea 3f 20 20 61  |=h(x-1;y)...?  a|
000007f0  64 64 20 20 20 20 20 20  20 72 31 34 2c 72 33 2c  |dd       r14,r3,|
00000800  23 31 3c 3c 32 34 20 20  20 20 20 20 20 20 20 20  |#1<<24          |
00000810  20 3b 20 72 31 34 3d 28  78 2b 31 20 6d 6f 64 20  | ; r14=(x+1 mod |
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00000a60  31 0d 02 6c 1a 20 20 61  64 64 20 20 20 20 20 20  |1..l.  add      |
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00000aa0  33 2c 72 33 2c 23 31 3c  3c 32 34 3a 62 4e 45 20  |3,r3,#1<<24:bNE |
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00000b10  2b 31 20 6d 6f 64 32 35  35 29 3c 3c 32 34 2c 20  |+1 mod255)<<24, |
00000b20  63 6f 6e 74 69 6e 75 65  20 69 66 20 3c 3e 30 0d  |continue if <>0.|
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00000b40  31 33 21 2c 7b 72 30 2d  72 35 2c 70 63 7d 5e 0d  |13!,{r0-r5,pc}^.|
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00000b80  69 72 6f 6e 6d 65 6e 74  20 4d 61 70 70 69 6e 67  |ironment Mapping|
00000b90  20 3e 0d 02 bc 1f 3b 2f  2f 2f 2f 2f 2f 2f 2f 2f  | >....;/////////|
00000ba0  2f 2f 2f 2f 2f 2f 2f 2f  2f 2f 2f 2f 2f 2f 2f 2f  |////////////////|
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00000d50  20 20 20 20 20 20 20 20  20 20 3b 20 72 35 3d 79  |          ; r5=y|
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00000d80  36 2c 23 30 20 20 20 20  20 20 20 20 20 20 20 20  |6,#0            |
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00000dc0  32 34 20 20 20 20 20 20  20 3b 20 72 31 31 3d 6c  |24       ; r11=l|
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00000df0  31 32 2c 72 33 2c 72 36  2c 6c 73 72 20 23 32 34  |12,r3,r6,lsr #24|
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00000e30  20 20 20 20 20 20 20 20  20 3b 20 4c 6f 61 64 20  |         ; Load |
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00001530  30 2d 32 35 36 20 20 20  20 20 20 20 20 20 20 3b  |0-256          ;|
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00001560  31 3c 3c 32 34 3a 62 4e  45 20 64 72 61 77 5f 79  |1<<24:bNE draw_y|
00001570  20 20 20 20 20 20 20 3b  20 79 2b 3d 31 3c 3c 32  |       ; y+=1<<2|
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00001cd0  5d 3a 3d 22 22 0d ff                              |]:=""..|
00001cd7