Block Floating-Point Format
D-8
ADSP-BF53x/BF56x Blackfin Processor Programming Reference
number of redundant sign bits is less than two. In this example,
SB
= +1 after processing, indicating the block of data must be
shifted right one bit to maintain the two guard bits.
• If
SB
were 0 after processing, the block would have to be shifted
two bits right. In either case, the block exponent is updated to
reflect the shift.
Figure D-5. Block Floating-point Adjustment
Sign Bit
One Guard Bit
0x1FFF = 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1
0x3FFF = 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0x07FF = 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1
2. Shift right to restore guard bits
Sign Bit
Two Guard Bits
0x0FFF = 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1
0x1FFF = 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1
0x03FF = 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1
1. Check for bit growth
Exponent = +2, SB = +2
Exponent = +1, SB = +1
Exponent = +4, SB = +1
EXPADJ instruction checks
exponent, adjusts SB
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...