5.6.6. VMRS and VMSR

Transfer contents between an ARM register and a NEON and VFP system register.

Syntax

VMRS{cond} Rd, extsysreg
VMSR{cond} extsysreg, Rd

where:

cond

is an optional condition code (see Condition codes).

extsysreg

is the NEON and VFP system register, usually FPSCR, FPSID, or FPEXC (see NEON and VFP system registers).

Rd

is the ARM register. Rd must not be r15.

It can be APSR_nzcv, if extsysreg is FPSCR. In this case, the floating-point status flags are transferred into the corresponding flags in the ARM APSR.

Usage

The VMRS instruction transfers the contents of extsysreg into Rd.

The VMSR instruction transfers the contents of Rd into extsysreg.

Note

These instructions stall the ARM until all current NEON or VFP operations complete.

Examples

    VMRS    r2,FPCID
    VMRS    APSR_nzcv, FPSCR     ; transfer FP status register to ARM APSR
    VMSR    FPSCR, r4
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