Analog Devices ADSP-BF53x Blackfin Reference page 475

Table 13-2. Input Register Bit Field Definitions
1
scene_reg:
2
pattern_reg:
1 where s = scene bit field (32 bits)
2 where:
–p = position of pattern bit field LSB in scene_reg (valid range 0 through 31)
–L = length of pattern bit field (valid range 0 through 31)
The operation reads the pattern bit field of length L from the scene bit
field, with the pattern LSB located at bit p of the scene. See "Example",
below, for more.
Boundary Case
If (p + L) > 32: In the zero-extended and sign-extended versions of the
instruction, the architecture assumes that all bits to the left of the
are zero. In such a case, the user is trying to access more bits
scene_reg
than the register actually contains. Consequently, the architecture fills any
undefined bits beyond the MSB of the
The Bit Field Extraction instruction does not modify the contents of the
two source registers. One of the source registers can also serve as
Options
The user has the choice of using the (X) syntax to perform sign-extend
extraction or the (Z) syntax to perform zero-extend extraction.
Flags Affected
This instruction affects flags as follows.
• is set if result is zero; cleared if nonzero.
AZ
• is set if result is negative; cleared if non-negative.
AN
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
31................24 23................16
ssss ssss ssss ssss
Bit Operations
15..................8
ssss ssss
xxxp pppp
with zeros.
scene_reg
7....................0
ssss ssss
xxxL LLLL
.
dest_reg
13-17