Miles Sound System SDK 7.2a

DDK Function: 303H Parse Environment String

Discussion

Input:

AX = 303H
BX = Driver number
DOS environment string copied by application to scratch area

Output:

AX = 1: String parsed successfully, IO member validated in VDI_HDR
AX = 0: String could not be parsed successfully, IO invalid

This function may be used to give the driver access to an operating system environment variable, to aid in identifying the correct I/O parameters to be used with the supported device.

As an example, systems with Creative Labs Sound Blaster-family devices installed normally have an MS-DOS environment variable called "BLASTER" which details, among other things, the I/O address, IRQ level, and DMA channel settings of the board. Consequently, all Sound Blaster-compatible sound drivers contain an embedded ASCII string 'BLASTER' at the address indicated by the DDT's *environment_string member. Before resorting to auto-detection, the application should perform a getenv call with this string and, if the result is not NULL, copy the resulting string to the VDI_HDR structure's scratch workspace and call this function. Assuming the function returns successfully, the VDI_HDR IO structure will contain the information from the parsed environment string.

Group: DOS Sound Driver Generic Initialization Interface
Related Structures: VDI_HDR