; cb256.ah,v 1.7 2004/02/27 03:22:18 ecen2120 Exp

MakeCB	macro
	ds.b	258
        endm

    xref   SetCBEmpty
; Set a circular buffer empty
;   On entry-
;     a0 addresses the buffer
;   On exit-
;     The buffer is empty

    xref   CBFull
; Count the number of bytes in use in a circular buffer
;   On entry-
;     a0 addresses the buffer
;   On exit-
;     d0=number of bytes in use in the buffer

    xref   CBEmpty
; Count the number of empty bytes in a circular buffer
;   On entry-
;     a0 addresses the buffer
;   On exit-
;     d0=number of empty bytes in the buffer

    xref   CBInsert
; Insert a character into a circular buffer
;   On entry-
;     a0 addresses the buffer
;     d0 contains the character to be inserted
;   If the buffer is full then on exit-
;     No insertion has been made
;   Else on exit-
;     d0 has been stored into the buffer
;     The number of characters in the buffer has been increased by 1
;     The current content of d0 is undefined

    xref   CBExtract
; Extract a character from a circular buffer
;   On entry-
;     a0 addresses the buffer
;   If the buffer is empty then on exit-
;     d0 is undefined
;   Else on exit-
;     d0 contains the character extracted
;     The number of characters in the buffer has been reduced by 1