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] .
This register is present only when AArch32 is supported at any Exception level. Otherwise, direct accesses to CNTVCT are UNDEFINED.
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 EL2Enabled() && !ELUsingAArch32(EL2) && HCR_EL2.<E2H,TGE> != '11' && CNTHCTL_EL2.EL1TVCT == '1' then
AArch64.AArch32SystemAccessTrap(EL2, 0x04);
else
return CNTVCT;
elsif PSTATE.EL == EL1 then
if EL2Enabled() && !ELUsingAArch32(EL2) && 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;