| ; Copyright 2019 Google LLC |
| ; |
| ; Licensed under both the 3-Clause BSD License and the GPLv2, found in the |
| ; LICENSE and LICENSE.GPL-2.0 files, respectively, in the root directory. |
| ; |
| ; SPDX-License-Identifier: BSD-3-Clause OR GPL-2.0 |
| |
| .code |
| |
| ; See measurereadlatency_x86_64.S for the commented and formatted version. |
| ; |
| ; One difference: the `address` argument is passed in rcx on Win64. |
| public MeasureReadLatency |
| MeasureReadLatency: |
| ; rcx = address |
| |
| mfence |
| lfence |
| rdtsc |
| shl rdx, 32 |
| or rax, rdx |
| mov r8, rax |
| lfence |
| mov al, byte ptr [rcx] |
| lfence |
| rdtsc |
| shl rdx, 32 |
| or rax, rdx |
| sub rax, r8 |
| ret |
| |
| end |
