Legacy Document

Inside Macintosh: Devices /

Chapter 1 - Device Manager / Device Manager Reference

Device Manager Functions / Writing and Installing Device Drivers

Fetch

You can use the Fetch routine to get the next character from the data buffer.

DESCRIPTION

The Fetch routine gets the next character from the data buffer pointed to by the ioBuffer field of the parameter block of the pending request. It increments the ioActCount field by 1. If the ioActCount field equals the ioReqCount field, this routine sets bit 15 of register D0. After receiving the last byte request, the driver should jump to the IODone routine.

Registers on entry
A1	Pointer to the device control entry

Registers on exit
D0	Character fetched; bit 15 = 1 if this is the last character in the buffer

Jump vector
JFetch