---
name: "Tspi_TPM_PcrRead"
section: "3"
platform: "linux"
package: "libtspi-dev"
version: "0.3.15-0.4"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/Tspi_TPM_PcrRead"
---

# Tspi\_TPM\_PcrRead(3)

read the value in a PCR register

TCG Software Stack Developer's Reference

## NAME

Tspi\_TPM\_PcrRead - read the value in a PCR register

## SYNOPSIS

```
#include <tss/platform.h>
#include <tss/tcpa_defines.h>
#include <tss/tcpa_typedef.h>
#include <tss/tcpa_struct.h>
#include <tss/tss_typedef.h>
#include <tss/tss_structs.h>
#include <tss/tspi.h>

TSS_RESULT Tspi_TPM_PcrRead(TSS_HTPM hTPM,              UINT32 ulPcrIndex,
                            UINT32*  pulPcrValueLength, BYTE** prgbPcrValue);
```

## DESCRIPTION

**Tspi\_TPM\_PcrRead** reads a PCR register to find the current values.

## PARAMETERS

### hTPM

The *hTPM* parameter is used to specify the handle of the TPM object. The command to get the TPM to test itself will be sent here.

### ulPcrIndex

The *ulPcrIndex* parameter is the index of the PCR to read.

### pulPcrValueLength

The *pulPcrValueLength* parameter receives the length in bytes of the *prgbPcrValue* parameter.

### prgbPcrValue

The *prgbPcrValue* parameter receives a pointer to the memory block containing the PCR data.

## RETURN CODES

**Tspi\_TPM\_PcrRead** returns TSS\_SUCCESS on success, otherwise one of the following values is returned:

- TSS\_E\_INVALID\_HANDLE

  *hTPM* is not a valid handle.

- TSS\_E\_INTERNAL\_ERROR

  An internal SW error has been detected.

- TSS\_E\_BAD\_PARAMETER

  One or more parameters is bad.

## CONFORMING TO

**Tspi\_TPM\_PcrRead** conforms to the Trusted Computing Group Software Specification version 1.1 Golden

## SEE ALSO

[**Tspi\_TPM\_PcrExtend**(3)](/Tspi_TPM_PcrExtend/3.md).