fctidz

Floating Convert to Integer Doubleword with Round to Zero

fctidz FRT, FRB

Converts Double to 64-bit Int (Truncate).

Details

Floating Convert to Integer Doubleword with Round to Zero converts the double-precision floating-point value in FRB to a signed 64-bit integer, truncating toward zero (round-to-zero), and places the result in FRT as a floating-point representation. FPSCR is updated with FPRF, FR, and FI flags; exception flags (XX, ZX) are set if applicable.

Pseudocode Operation

FRT ← (int64_t)truncate(FRB)
Update FPSCR[FPRF, FR, FI, XX, ZX]

Programming Note

The fctidz instruction converts a double-precision floating-point value to a signed 64-bit integer, rounding towards zero. If the source value is NaN, it returns 0x8000_0000_0000_0000 and sets VXCVI to 1. If the rounded value exceeds the range of a 64-bit signed integer, it saturates to either 0x7FFF_FFFF_FFFF_FFFF or 0x8000_0000_0000_0000.

Example

fctidz f1, f3

Encoding

Binary Layout
63
0
FRT
6
0
11
FRB
16
815
21
/
31
 
Format X-form
Opcode 0xFC00065E
Extension Floating-Point
Registers Altered FPSCR

Operands

  • FRT
    Target
  • FRB
    Source