denbcd

Decimal Encode BCD

denbcd FRT, FRB, S

Encodes a DFP number into BCD format.

Encoding

Binary Layout

59

0:5

FRT

6:10

S

11:15

FRB

16:20

834

21:30

/

31

 

Format X-form

Opcode 0xEC000684

Extension Decimal Floating-Point

Operands

• FRT
  Target
• FRB
  Source
• S
  Sign Control

Example

denbcd f1, f3, 0

Registers Altered

FPSCR

Related

More in Decimal Floating-Point

Reference

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

Description

Encodes a decimal floating-point number in FRB into Binary Coded Decimal (BCD) format and places the result in FRT. The sign control field S determines how the sign is encoded. This instruction handles conversion of the coefficient and exponent into BCD representation. FPSCR is updated based on invalid operations.

Operation

dfp_value ← FRB
sign ← extract_sign(dfp_value)
coefficient ← extract_coefficient(dfp_value)
exponent ← extract_exponent(dfp_value)
bcd_result ← encode_to_bcd(sign, coefficient, exponent, S)
FRT ← bcd_result
FPSCR ← updated based on encoding result

Programming Note

The denbcd instruction is used to convert a Binary-Coded Decimal (BCD) value into Data-Packed Decimal (DPD) format. Ensure that the input BCD value in FRB is correctly formatted and aligned as required by the instruction. This operation does not raise exceptions for valid inputs but may require careful handling of special cases like overflow or invalid data.