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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:
| 63 | 62 | 61 | 60 | 59 | 58 | 57 | 56 | 55 | 54 | 53 | 52 | 51 | 50 | 49 | 48 | 47 | 46 | 45 | 44 | 43 | 42 | 41 | 40 | 39 | 38 | 37 | 36 | 35 | 34 | 33 | 32 |
| Virtual count value | |||||||||||||||||||||||||||||||
| Virtual count value | |||||||||||||||||||||||||||||||
| 31 | 30 | 29 | 28 | 27 | 26 | 25 | 24 | 23 | 22 | 21 | 20 | 19 | 18 | 17 | 16 | 15 | 14 | 13 | 12 | 11 | 10 | 9 | 8 | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
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>
| coproc | CRm | opc1 |
|---|---|---|
| 0b1111 | 0b1110 | 0b0001 |
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;