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CNTVCT, Counter-timer Virtual Count register

The CNTVCT characteristics are:

Purpose

Holds the 64-bit virtual count value. The virtual count value is equal to the physical count value minus the virtual offset visible in CNTVOFF.

Configuration

AArch32 System register CNTVCT bits [63:0] are architecturally mapped to AArch64 System register CNTVCT_EL0[63:0] .

The value of this register is the same as the value of CNTPCT in the following conditions:

  • When EL2 is not implemented.
  • When EL2 is implemented and is using AArch64, HCR_EL2.{E2H, TGE} is {1, 1}, and this register is read from Non-secure EL0.

All reads to the CNTVCT occur in program order relative to reads to CNTVCTSS or CNTVCT.

Attributes

CNTVCT is a 64-bit register.

Field descriptions

The CNTVCT bit assignments are:

6362616059585756555453525150494847464544434241403938373635343332
Virtual count value
Virtual count value
313029282726252423222120191817161514131211109876543210

Bits [63:0]

Virtual count value.

Accessing the CNTVCT

Accesses to this register use the following encodings:

MRRC{<c>}{<q>} <coproc>, {#}<opc1>, <Rt>, <Rt2>, <CRm>

coprocCRmopc1
0b11110b11100b0001
if PSTATE.EL == EL0 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTKCTL_EL1.EL0VCTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        else
            AArch64.AArch32SystemAccessTrap(EL1, 0x04);
    elsif ELUsingAArch32(EL1) && CNTKCTL.PL0VCTEN == '0' then
        if EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.TGE == '1' then
            AArch64.AArch32SystemAccessTrap(EL2, 0x04);
        elsif EL2Enabled() && ELUsingAArch32(EL2) && HCR.TGE == '1' then
            AArch32.TakeHypTrapException(0x00);
        else
            UNDEFINED;
    elsif EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> == '11' && CNTHCTL_EL2.EL0VCTEN == '0' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x04);
    elsif !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTHCTL_EL2.EL1TVCT == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x04);
    else
        return CNTVCT;
elsif PSTATE.EL == EL1 then
    if !ELUsingAArch32(EL1) && !(EL2Enabled() && HCR_EL2.<E2H,TGE> == '11') && CNTHCTL_EL2.EL1TVCT == '1' then
        AArch64.AArch32SystemAccessTrap(EL2, 0x04);
    else
        return CNTVCT;
elsif PSTATE.EL == EL2 then
    return CNTVCT;
elsif PSTATE.EL == EL3 then
    return CNTVCT;
              


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