STATUSREQUEST STRUC
srLength db ? ;length of record, in bytes
srUnit db ? ;not used
srFunction db 0Ah ;function number
srStatus dw ? ;status
srReserved db 8 dup(?) ;reserved
STATUSREQUEST ENDS
Output Status (Device-Driver Function 0Ah) specifies whether any characters are in the device-output buffer.
This function is required for character-device drivers only.
srLength
Specifies the length, in bytes, of the STATUSREQUEST structure.
srUnit
Not used.
srFunction
Specifies the Output Status function: 0Ah.
srStatus
Specifies the status of the completed function. If the output buffer has any characters, the driver must set the busy bit (bit 9), indicating that the device is busy. If the output buffer has no characters, the busy bit must be zero. In both cases, the driver must set the done bit (bit 8).
If the function is not successful, the driver must set both the error and done bits (bits 15 and 8) and copy an error value to the low-order byte.
srReserved
Reserved; do not use.
Device-Driver Function 06h Input Status
Interrupt 21h Function 4407h Check Device Output Status