AddBuffers

Changes the number of buffers for a file system (V36)

Adds buffers to a file system. If it succeeds, the number of current buffers is returned in IoErr(). Note that "number" may be negative. The amount of memory used per buffer, and any limits on the number of buffers, are dependent on the file system in question. If the call succeeds, the number of buffers in use on the file system will be returned by IoErr().

filesystem

Name of device to add buffers to (with ':'), e.g. "DF0:"

number

Number of buffers to add. May be negative.

success

Success or failure of command.

The number of buffers may not translate into actual memory being allocated or released by the file system. The file system may delay changes in the nominal number of buffers or may ignore the change request altogether. What exactly a single "buffer" element stands for in terms of memory usage or what purpose it will be used is up to the respective file system. Also, file systems may not reveal how many buffers are in use.

The V36 ROM file system (FFS/OFS) doesn't return the right number of buffers unless preceded by an AddBuffers(fs,-1) (in-use buffers aren't counted). This is fixed in V37.

The V37 and before ROM file system doesn't return success, it returns the number of buffers. The best way to test for this is to consider 0 (FALSE) failure, -1 (DOSTRUE) to mean that IoErr() will have the number of buffers, and any other positive value to be the number of buffers. It may be fixed in some future ROM revision.

IoErr()