ddedpdq

Decimal Decode DPD Quad-Precision

ddedpdq vD, vB, SP

Decodes BCD to 128-bit DFP.

Details

Decodes a binary-coded decimal (BCD) value from vB into a 128-bit decimal floating-point number, storing the result in vD. The sign field SP specifies how to interpret the sign encoding in the BCD representation. The instruction converts BCD digits to the internal DFP representation. The instruction is part of the Decimal Floating-Point extension.

Pseudocode Operation

vD ← DecodeDFP128(vB, SP)

Programming Note

The ddedpdq instruction is used to convert a DPD-encoded decimal value from one register to BCD format in another. Ensure that the source register contains valid DPD data; otherwise, the result will be undefined. This operation does not require any specific privilege level but may alter the FPSCR register based on the conversion outcome.

Example

ddedpdq vd, vb, 0

Encoding

Binary Layout
63
0
vD
6
SP
11
vB
16
322
21
/
31
 
Format X-form
Opcode 0xFC000284
Extension Decimal Floating-Point
Registers Altered FPSCR

Operands

  • vD
    Target
  • vB
    Source
  • SP
    Sign