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Mailing lists / fpc-pascal / 2001-08

Interrupts under Go32

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Shifted Soul

Hi
I read the documentation about how to write ISRs in Go32. I found this snip of code :

------!Cut!-------
backupDS : Word; external name '___v2prt0_ds_alias'; ------!Cut!-------

(In the Standard units reference manual > The Go32 unit > Hardware interrupts)
What is "___v2prt0_ds_alias" ? What kind of value it can have ? in which (external object) file it is found ?

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Thomas Schatzl
to Shifted Soul

----- Original Message -----
From: "Shifted Soul"
Subject: [fpc-pascal]Interrupts under Go32

Hi

Show quoted text 11 lines
I read the documentation about how to write ISRs in Go32. I found this snip of code : ------!Cut!------- backupDS : Word; external name '___v2prt0_ds_alias'; ------!Cut!------- (In the Standard units reference manual > The Go32 unit > Hardware interrupts) What is "___v2prt0_ds_alias" ? What kind of value it can have ? in which (external object) file it is found ?

The go32v2 environment guarantees that this selector specifies a valid descriptor to the data segment (or the memory area used as ds in fpc) even during interrupts, exceptions etc afair.

Don't assume any specific values for it, may be different every time the program starts up.

It is defined in prt0.s in the rtl source tree (prt0.o).

Regards,
Thomas

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