Analog Devices ADSP-BF53x Blackfin, Reference

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ADSP-BF53x/BF56x Blackfin Processor Programming Reference 19-9
Vector Operations
Functional Description
The Compare-Select (
VIT_MAX
) instruction selects the maximum values of
pairs of 16-bit operands, returns the largest values to the destination regis-
ter, and serially records in
A0.W
the source of the maximum.This operation
performs signed operations. The operands are compared as
two’s-complements.
Versions are available for dual and single 16-bit operations. Whereas the
dual versions compare four operands to return two maxima, the single ver-
sions compare only two operands to return one maximum.
The Accumulator extension bits (bits 39–32) must be cleared before exe-
cuting this instruction.
This operation is illustrated in Table 19-4 and Table 19-5 .
Dual 16-Bit Operand Behavior
The ASL version shifts
A0
left two bit positions and appends two LSBs to
indicate the source of each maximum as shown in Table 19-6 and
Table 19-7 .
Table 19-4. Source Registers Contain
31................24 23................16 15..................8 7....................0
src_reg_0 y1 y0
src_reg_1 z1 z0
Table 19-5. Destination Register Contains
31................24 23................16 15..................8 7....................0
dest_reg Maximum, y1 or y0 Maximum, z1 or z0