ADSP-BF53x/BF56x Blackfin Processor Programming Reference
18-33
Video Pixel Operations
The only valid input source register pairs are
R1:0
and
R3:2
.
The Quad 8-Bit Subtract instruction provides byte alignment directly in
the source register pairs
src_reg_0
and
src_reg_1
based on index registers
I0
and
I1
.
• The two LSBs of the
I0
register determine the byte alignment for
source register pair
src_reg_0
(typically
R1:0
).
• The two LSBs of the
I1
register determine the byte alignment for
source register pair
src_reg_1
(typically
R3:2
).
The relationship between the I-register bits and the byte alignment is
illustrated shown in
Table 18-26
.
In the default source order case (for example, not the (R) syntax), assume a
source register pair contains the data shown in
Table 18-26
.
This instruction prevents exceptions that would otherwise be caused by
misaligned 32-bit memory loads issued in parallel.
Table 18-25. Destination Registers Receive
31................24
23................16
15..................8
7....................0
dest_reg_0:
y1 - z1
y0 - z0
dest_reg_1:
y3 - z3
y2 - z2
Table 18-26. I-register Bits and the Byte Alignment
The bytes selected are
src_reg_pair_HI
src_reg_pair_LO
Two LSB’s of I0 or I1
byte7
byte6
byte5
byte4
byte3
byte2
byte1
byte0
00b:
byte3
byte2
byte1
byte0
01b:
byte4
byte3
byte2
byte1
10b:
byte5
byte4
byte3
byte2
11b:
byte6
byte5
byte4
byte3
Summary of Contents for ADSP-BF53x Blackfin
Page 38: ...Conventions xxxviii ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 134: ...System Reset and Powerup 3 18 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 324: ...Instruction Overview 7 20 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 486: ...Instruction Overview 13 28 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 512: ...Instruction Overview 14 26 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 604: ...Instruction Overview 15 92 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 688: ...Instruction Overview 18 48 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 742: ...Instruction Overview 19 54 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 752: ...Examples 20 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 790: ...ADSP BF535 Flags A 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 800: ...Performance Monitor Registers B 10 ADSP BF53x BF56x Blackfin Processor Programming Reference...
Page 1042: ...Index I 40 ADSP BF53x BF56x Blackfin Processor Programming Reference...