modsw

Modulo Signed Word

modsw RT, RA, RB

Calculates remainder of signed word division.

Encoding

Binary Layout

31

0:5

RT

6:10

RA

11:15

RB

16:20

779

21:30

/

31

 

Format X-form

Opcode 0x7C000616

Extension Base

Operands

• RT
  Target
• RA
  Dividend
• RB
  Divisor

Example

modsw r3, r4, r5

Related

More in Base

Reference

View in PowerISA v3.1C Specification ↗ OPF Power ISA v3.1C

Description

The 32-bit dividend is (RA)32:63. The 32-bit divisor is (RB)32:63. The 32-bit remainder of the dividend divided by the divisor is placed into RT32:63. The contents of RT0:31 are undefined.

Operation

dividend = (RA)32:63
 divisor = (RB)32:63
 if dividend >= 0 then
    quotient = floor(dividend / divisor)
 else
    quotient = ceil(dividend / divisor)
 RT32:63 <- dividend - (quotient * divisor)
 RT0:31 <- undefined

Programming Note

If an attempt is made to perform any of the divisions 0x8000_0000 % -1 or <anything> % 0, then the contents of register RT are undefined.