; C02 Module direct Assembly Language Routines for run6502 emulator
; This is the reference implementation of the direct module 
; Requires external function FSCMD and FSDRVN (fileio.h02)

        SUBROUTINE DIRECT

;getcwd(drv, &dir) - Get Current Directory
;Args: A = Drive Identifier
;      Y,X = Pointer to String
;Returns: A = Result (0 = Success, $FF = Failure)
;         Y = Error Code (0 = None)
GETCWD: JSR FSDRVN        ;Convert Drive Letter to Drive Number
        BCS .DRVERR       ;If Invalid Return Error
        LDA #'T'          ;Set Command to GETCWD
.FSCMDX JSR FSCMD         ;Execute Command
        TXA               ;Return Length of Name
.DRVERR RTS

;chdir(drv, &dir) - Get Current Directory
;Args: A = Drive Identifier
;      Y,X = Pointer to String
;Returns: A = Result (0 = Succes, $FF = Failure)
;         Y = Error Code (0 = None)
CHDIR:  JSR FSDRVN        ;Convert Drive Letter to Drive Number
        BCS .DRVERR       ;If Invalid Return Error
        LDA #'U'          ;Set Command to GETCWD
        BNE .FSCMDX       ;Execute Command and Return Result

;rmdir(drv, &dir) - Create Directory
;Args: A = Drive Identifier
;      Y,X = Address of Directory Name String
;Returns: A = Error Code (0 = None)
RMDIR:  SEC               ;Set Mode to RMDIR
        BCS .MRDIR        ;Execute MKRMDIR and Return Result

;mkdir(drv, &dir) - Create Directory
;Args: A = Drive Identifier
;      Y,X = Address of Directory Name String
;Returns: A = Error Code (0 = None)
MKDIR:  CLC               ;Set Mode to MKDIR
.MRDIR  PHP               ;Save Status Register
        JSR FSDRVN        ;Convert Drive Letter to Drive Number
        BCS .DRVERR       ;If Invalid Return Error
        PLP               ;Restore Status Register
        LDA #'X'          ;Set Command to MKRMDIR
        BNE .FSCMDX       ;Execute Command and Return Result

.PLAERR PLP               ;Restore Status Register
        RTS               ;and Return