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# CNTCV, Counter Count Value register

The CNTCV characteristics are:

## Purpose

Indicates the current count value.

## Configuration

The power domain of CNTCV is IMPLEMENTATION DEFINED.

On a reset of the reset domain in which an RW instance of this register is implemented, RW fields in the register reset to UNKNOWN values. The register is not affected by a reset of any other reset domain. For more information see 'Power and reset domains for the system level implementation of the Generic Timer' in Chapter I1 of the Arm® Architecture Reference Manual, Armv8, for Armv8-A architecture profile.

## Attributes

CNTCV is a 64-bit register.

## Field descriptions

The CNTCV 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
CountValue
CountValue
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

#### CountValue, bits [63:0]

Indicates the counter value.

This field resets to an architecturally UNKNOWN value.

## Accessing the CNTCV

Frame | Accessibility
--- | ---
CNTControlBase | RW
CNTReadBase | RO

A write to CNTCV must be visible in the CNTPCT register of each running processor in a finite time.

For the instance of the register in the CNTControlBase frame:

- In a system that supports Secure and Non-secure memory maps the CNTControlBase frame, and therefore this register instance, is implemented only in the Secure memory map.
- If the counter is enabled, the effect of writing to the register is UNKNOWN.

In an implementation that supports 64-bit atomic memory accesses, this register must be accessible using a 64-bit atomic access.

#### CNTCV can be accessed through the memory-mapped interfaces:

Component | Frame | Offset | Instance | Range
--- | --- | --- | --- | ---
Timer | CNTControlBase | 0x008 | CNTCV | 63:0

Access on this interface is RW.

Component | Frame | Offset | Instance | Range
--- | --- | --- | --- | ---
Timer | CNTReadBase | 0x000 | CNTCV | 63:0

Access on this interface is RO.

AArch32 Registers | AArch64 Registers | AArch32 Instructions | AArch64 Instructions | Index by Encoding | External Registers | External Registers by Offset | Registers by Functional Group | Proprietary Notice

15/04/2019 16:47; 8c23526ba8a13a72aada4137daf3e3977b49036e

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