Optimized the condes routine, because it is used to schedule interrupt

handlers on many platforms, so too many cycles are evil.

git-svn-id: svn://svn.cc65.org/cc65/trunk@2962 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/runtime/condes.s b/libsrc/runtime/condes.s
index c9e373277abb031e9e27116073a94c705ace59be..99c4a6b85d312b5c7e1424e70c538a39061b8a8d 100644 (file)
--- a/libsrc/runtime/condes.s
+++ b/libsrc/runtime/condes.s
@@ -4,9 +4,9 @@
 ; CC65 runtime: Support for calling module constructors/destructors
 ;
 ; The condes routine must be called with the table address in a/x and the
-; size of the table in y. The current implementation limits the table size
-; to 254 bytes (127 vectors) but this shouldn't be problem for now and may
-; be changed later.
+; size of the table (which must not be zero!) in y. The current implementation
+; limits the table size to 254 bytes (127 vectors) but this shouldn't be
+; problem for now and may be changed later.
 ;
 ; libinit and libdone call condes with the predefined module constructor and
 ; destructor tables, they must be called from the platform specific startup
@@ -27,11 +27,12 @@
 
 .proc  initlib
 
+       ldy     #<(__CONSTRUCTOR_COUNT__*2)
+               beq     exit
        lda     #<__CONSTRUCTOR_TABLE__
        ldx     #>__CONSTRUCTOR_TABLE__
-       ldy     #<(__CONSTRUCTOR_COUNT__*2)
-       bne     condes
-       rts
+        jmp     condes
+exit:   rts
 
 .endproc
 
@@ -41,57 +42,41 @@
 
 .proc  donelib
 
-       lda     #<__DESTRUCTOR_TABLE__
-       ldx     #>__DESTRUCTOR_TABLE__
-       ldy     #<(__DESTRUCTOR_COUNT__*2)
-       bne     condes
-       rts
+       ldy     #<(__DESTRUCTOR_COUNT__*2)
+       beq     initlib::exit
+       lda     #<__DESTRUCTOR_TABLE__
+       ldx     #>__DESTRUCTOR_TABLE__
+       jmp     condes
 
 .endproc
 
 
 ; --------------------------------------------------------------------------
-; Generic table call handler. We cannot use callax here, since condes is also
-; used for interrupt handlers, and callax clobbers ptr1.
+; Generic table call handler. Since the routine is also used to call a table
+; of interrupt handlers, it uses heavily self modifying code for performance
+; reasons. It will go into the data segment for this reason ...
+; NOTE: The routine must not be called if the table is empty!
 
-.proc  condes
+.data
 
-       sta     getbyt+1
-       stx     getbyt+2
-       sty     index
+.proc  condes
 
-loop:  ldy     index
-       beq     done
-       dey
-       jsr     getbyt
+       sta     fetch1+1
+       stx     fetch1+2
+       sta     fetch2+1
+       stx     fetch2+2
+loop:   dey
+fetch1: lda     $FFFF,y                 ; Patched at runtime
         sta     jmpvec+2
-       dey
-       jsr     getbyt
+       dey
+fetch2: lda     $FFFF,y                 ; Patched at runtime
         sta     jmpvec+1
-       sty     index
-       jsr     jmpvec
-.if (.cpu .bitand ::CPU_ISET_65SC02)
-       bra     loop
-.else
-       jmp     loop
-.endif
-
-done:  rts
+               sty     index+1
+jmpvec: jsr            $FFFF                   ; Patched at runtime
+index:         ldy     #$FF                    ; Patched at runtime
+               bne     loop
+        rts
 
 .endproc
 
 
-; --------------------------------------------------------------------------
-; Data. The getbyte and jmpvec routines are placed in the data segment
-; cause they're patched at runtime.
-
-.bss
-
-index: .byte   0
-
-.data
-
-getbyt:        lda     $FFFF,y
-       rts
-
-jmpvec: jmp     $0000