TAL Reference Manual

Expressions

TAL Reference Manual—526371-001

4-30

Usage Considerations

Table 4-14 lists the bit-shift operators you can specify.

For signed left shifts (<<), programs that run on TNS/R systems use unsigned left shifts

('<<').

Bit-shift operations include:

Examples of Bit Shifts

1. This unsigned left shift shows how zeros fill the vacated bits from the right:

Initial value = 0 010 111 010 101 000

'<<' 2 = 1 011 101 010 100 000

2. This unsigned right shift shows how zeros fill the vacated bits from the left:

Initial value = 1 111 111 010 101 000

'>>' 2 = 0 011 111 110 101 010

Table 4-14. Bit-Shift Operators

Operator Function Result

‘<<‘ Unsigned left shift through

bit <0>

Zeros fill vacated bits from the right

‘>>’ Unsigned right shift Zeros fill vacated bits from the left.

<< Signed left shift through

bit <0> or bit <1>

Zeros fill vacated bits from the right. In

arithmetic overflow cases, the final value of bit

<0> is undefined (different for TNS/R

accelerated mode than for TNS systems).

>> Signed right shift Sign bit (bit <0>) unchanged; sign bit fills

vacated bits from the left

Operation User Action

Multiplication by powers of 2 For each power of 2, shift the field one bit to the left.

(Some data might be lost.)

Division by powers of 2 For each power of 2, shift the field one bit to the right

(Some data might be lost.)

Word-to-byte address conversion Shift the word address one bit to the left, using an

unsigned shift operator.