bcdcfz.

Decimal Convert from Zoned

bcdcfz. vD, vB, PS

Converts BCD Zoned format to Signed Packed BCD.

Encoding

Binary Layout

4

0:5

VRT

6:10

6

11:15

VRB

16:20

1

21:29

PS

30

385

31

 

Format VX-form

Opcode 0x10060581

Extension Vector BCD

Operands

• vD
  Target
• vB
  Source
• PS
  Sign
• VRT
  Target Vector Register
• VRB
  Source Vector Register

Example

bcdcfz. vd, vb, 0

Registers Altered

CR6

Related

More in Vector BCD

Reference

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

Description

The bcdcfz. instruction converts a zoned decimal value in VSR[VRB+32] to a packed decimal format and stores the result in VSR[VRT+32]. The conversion is based on the sign code and digit values of the source operand.

Operation

if MSR.VEC=0 then
    Vector_Unavailable()
inv_flag ← ((VSR[VRB+32].byte[15].nibble[0] < 0xA) & (PS=1)) | (VSR[VRB+32].byte[15].nibble[1] > 0x9)
MIN ← (PS=0) ? 0x30 : 0xF0
MAX ← (PS=0) ? 0x39 : 0xF9
do i = 0 to 14
    inv_flag ← inv_flag | (VSR[VRB+32].byte[i] < MIN) | (VSR[VRB+32].byte[i] > MAX)
end
if PS=0 then
    src_sign ← VSR[VRB+32].nibble[30].bit[1]
else
    src_sign ← (VSR[VRB+32].nibble[30] = 0b1011) | (VSR[VRB+32].nibble[30] = 0b1101)
eq_flag ← 1
do i = 0 to 14
    result.nibble[i] ← 0x0
end
do i = 0 to 15
    result.nibble[i+15] ← VSR[VRB+32].byte[i].nibble[1]
    eq_flag ← eq_flag & (VSR[VRB+32].byte[i].nibble[1]=0x0)
end
lt_flag ← (eq_flag=0) & (src_sign=1)
gt_flag ← (eq_flag=0) & (src_sign=0)
result.nibble[31] ← (src_sign=0) ? 0xC : 0xD
CR.bit[56] ← inv_flag ? 0b0 : lt_flag
CR.bit[57] ← inv_flag ? 0b0 : gt_flag
CR.bit[58] ← inv_flag ? 0b0 : eq_flag
CR.bit[59] ← inv_flag
VSR[VRT+32] ← inv_flag ? undefined : result

Programming Note

The bcdcfz. instruction is used to convert zoned decimal values to packed decimal format. Ensure that the source vector register (VRB) contains valid zoned decimal data, as invalid input can lead to undefined results and set the CR6 flags accordingly. This instruction operates at the user privilege level and requires the Vector Facility to be enabled; otherwise, a Vector_Unavailable exception is raised.