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.data
.text
.section regular,__DATA
.globl _ppc_zoom ;// name of the function to call by C program
; notes :
; this routine dynamically computes and applies a zoom filter
; do not use r0, r1, r2 and r13
; registers are not saved so the call to this function must be the last thing done in the calling C function
; parameters :
; r3 <=> unsigned int * frompixmap
; r4 <=> unsigned int * topixmap
; r5 <=> unsigned int sizeX (in pixels)
; r6 <=> unsigned int sizeY (in pixels)
; r7 <=> unsigned int * brutS
; r8 <=> unsigned int * brutD
; r9 <=> unsigned int buffratio
; globals after init
; r3 <=> frompixmap - 1 byte needed for preincremental fetch (replaces r3)
; r4 <=> topixmap - 1 byte needed for preincremental fetch (replaces r4)
; r5 <=> ax = x max in 16th of pixels (replaces old r5)
; r6 <=> ay = y max in 16th of pixels (replaces old r6)
; r15 <=> row size in bytes
; r16 <=> 0xFF00FF (mask for parallel 32 bits pixs computing)
; r30 <=> brutS - 1 byte needed for preincremental fetch (replaces r7)
; r31 <=> brutD - 1 byte needed for preincremental fetch (replaces r8)
_ppc_zoom:
; init
li r16,0xFF
mullw r17,r5,r6 ; number of pixels to compute
subi r30,r8,4
mulli r15,r5,4
slwi r16,r16,16
subi r5,r5,1
subi r6,r6,1
mtspr ctr,r17 ; number of pixels to compute
subi r31,r7,4
subi r4,r4,4
ori r16,r16,0xFF
mulli r5,r5,16
mulli r6,r6,16
boucle:
; computes dynamically the position to fetch
lwzu r8,4(r30) ; px2
lwzu r17,4(r31) ; px
lwzu r10,4(r30) ; py2
lwzu r29,4(r31) ; py
sub r8,r8,r17
sub r10,r10,r29
mullw r8,r8,r9
mullw r10,r10,r9
srawi r8,r8,16
srawi r10,r10,16
add r17,r17,r8
add r29,r29,r10
; if px>ax or py>ay or px<0 or py <0 goto outofrange
cmpw cr1,r17,r5
bgt- cr1,outofrange
cmpwi cr1,r17,0
blt- cr1,outofrange
cmpw cr1,r29,r6
bgt- cr1,outofrange
cmpwi cr1,r29,0
blt- cr1,outofrange
; computes the attenuation coeffs
andi. r8,r17,0x0F ;coefh
andi. r10,r29,0x0F ;coefv
subfic r18,r8,15 ;diffcoefh
subfic r7,r10,15 ;diffcoefv
mullw r21,r18,r7 ; coeff
mullw r22,r8,r7 ; coeff << 8
mullw r23,r18,r10 ; coeff << 16
mullw r24,r8,r10 ; coeff << 24
; calcul de l adresse du point d origine
srawi r17,r17,4 ; pertedec
srawi r29,r29,4 ; pertedec
srwi r7,r15,2
mullw r29, r29,r7
add r17,r17,r29
slwi r17,r17,2
add r17,r17,r3
; computes final pixel color
lwz r25,0(r17) ; chargement de col1 ->r25
and r8, r25,r16
lwz r26,4(r17) ; chargement de col2 ->r26
mullw r8, r8, r21
andi. r18, r25,0xFF00
add r17,r17,r15
and r10, r26,r16
mullw r18, r18, r21
lwz r27,0(r17) ; chargement de col3 ->r27
mullw r10, r10, r22
andi. r29, r26, 0xFF00
lwz r28,4(r17) ; chargement de col4 ->r28
add r8, r8,r10
mullw r29, r29, r22
and r10, r27,r16
add r18, r18, r29
mullw r10, r10, r23
andi. r29, r27, 0xFF00
add r8, r8,r10
mullw r29, r29, r23
and r10, r28,r16
add r18, r18, r29
mullw r10, r10, r24
andi. r29, r28, 0xFF00
add r8, r8,r10
mullw r29, r29, r24
srawi r7,r8,8
add r18, r18, r29
and r7, r7,r16
srawi r18, r18, 8
andi. r18,r18,0xFF00
or r7, r18, r7
b end ;goto end
; if out of range
outofrange:
li r7,0
end:
stwu r7, 4(r4)
bdnz+ boucle
blr
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