On 10/23/2017 02:21 AM, Wolf wrote:
On 23/10/17 02:53, Nikolay Nikolov wrote:
FPC trunk supports rdtscp. And if you're using a FPC version that
doesn't support an instruction, you can always hardcode it with 'db'
(make sure you add a comment with the real instruction to keep your
code readable), e.g:
db 0fh, 01h, 0f9h { rdtscp - not supported by FPC 3.0's inline
assembler }
Nikolay
db 0fh, 01h, 0f9h is a Delphi instruction, as far as I can make it
out. It does not work with FPC 3.00 - at least with the settings
Lazarus provides by default running under Linux.
What does work is
.byte 0x0F, 0x01, 0xF9 // read the Time-Stamp Counter rdtscp
(as op-code format,
// requires setting the
compiler switch -aas
// in Lazarus:
Options/Custom Options/All Options )
Yes, that's AT&T asm syntax. FPC supports both AT&T and Intel syntax
modes with the {$asmmode} directive:
https://www.freepascal.org/docs-html/prog/progsu3.html
AT&T is the default for historical reasons, but Intel also works fine.
Nikolay
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