Forgot to add the new module that contains em_load_driver.

git-svn-id: svn://svn.cc65.org/cc65/trunk@5795 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/em/em_load.s

@@ -0,0 +1,120 @@
+;
+; Ullrich von Bassewitz, 2012-07-22
+;
+; unsigned char __fastcall__ em_load_driver (const char* name)
+; /* Load an extended memory driver and return an error code */
+
+
+        .include        "em-kernel.inc"
+        .include        "em-error.inc"
+        .include        "modload.inc"
+        .include        "fcntl.inc"
+
+        .import         pushax
+        .import         pusha0
+        .import         incsp2
+        .import         _open
+        .import         _read
+        .import         _close
+
+
+
+;----------------------------------------------------------------------------
+; Variables
+
+.data
+
+ctrl:   .addr   _read
+        .res    2                       ; CALLERDATA
+        .res    2                       ; MODULE
+        .res    2                       ; MODULE_SIZE
+        .res    2                       ; MODULE_ID
+                   
+;----------------------------------------------------------------------------
+; Code
+
+.code
+
+.proc   _em_load_driver
+
+; Check if we do already have a driver loaded. This is an error. Do not
+; touch A/X because they contain the file name.
+
+        ldy     _em_drv
+        bne     @L0
+        ldy     _em_drv+1
+        beq     @L1
+@L0:    lda     #EM_ERR_INSTALLED
+        bne     @L4
+
+; Push the name onto the C stack and open the file. The parameter will get
+; removed by open().
+; ctrl.callerdata = open (name, O_RDONLY);
+
+@L1:    jsr     pushax
+        lda     #<O_RDONLY
+        jsr     pusha0
+        ldy     #4                      ; Argument size
+        jsr     _open
+        sta     ctrl + MOD_CTRL::CALLERDATA
+        stx     ctrl + MOD_CTRL::CALLERDATA+1
+
+; if (ctrl.callerdata >= 0) {
+
+        txa
+        bmi     @L3
+
+; /* Load the module */
+; Res = mod_load (&ctrl);
+
+        lda     #<ctrl
+        ldx     #>ctrl
+        jsr     _mod_load
+        pha
+
+; /* Close the input file */
+; close (ctrl.callerdata);
+
+        lda     ctrl + MOD_CTRL::CALLERDATA
+        ldx     ctrl + MOD_CTRL::CALLERDATA+1
+        jsr     _close
+
+; /* Check the return code */
+; if (Res == MLOAD_OK) {
+
+        pla
+        bne     @L3
+
+; Check the driver signature, install the driver.
+; Res = em_install (ctrl.module);
+
+        lda     ctrl + MOD_CTRL::MODULE
+        ldx     ctrl + MOD_CTRL::MODULE+1
+        jsr     _em_install
+
+; If em_install was successful, we're done
+
+        tax
+        beq     @L2
+
+; The driver didn't install correctly. Remove it from memory and return the
+; error code.
+
+        pha                             ; Save the error code
+        lda     _em_drv
+        ldx     _em_drv+1
+        jsr     _mod_free               ; Free the driver memory
+        jsr     em_clear_ptr            ; Clear em_drv
+        pla                             ; Restore the error code
+        ldx     #0                      ; We must return an int
+@L2:    rts                             ; Done
+
+; Open or mod_load failed. Return an error code.
+
+@L3:    lda     #<EM_ERR_CANNOT_LOAD
+@L4:    ldx     #0
+        rts
+
+.endproc
+
+