Added a specialized callirq routine

git-svn-id: svn://svn.cc65.org/cc65/trunk@2968 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/runtime/Makefile b/libsrc/runtime/Makefile
index 6226d35213285b3726b0aa19de2c8c5c7282ef0a..b42a5bba9e35c616352ae3b7c331f0b40dcb0373 100644 (file)
--- a/libsrc/runtime/Makefile
+++ b/libsrc/runtime/Makefile
@@ -41,6 +41,7 @@ OBJS =        add.o           \
                bneg.o          \
                bpushbsp.o      \
                call.o          \
+        callirq.o       \
         callmain.o      \
                compl.o         \
        condes.o        \

diff --git a/libsrc/runtime/callirq.s b/libsrc/runtime/callirq.s
new file mode 100644 (file)
index 0000000..9254d71
--- /dev/null
+++ b/libsrc/runtime/callirq.s
@@ -0,0 +1,53 @@
+;
+; Ullrich von Bassewitz, 2004-04-04
+;
+; CC65 runtime: Support for calling special irq routines declared as condes
+; type 2.
+;
+; There are two reasons, why this is a separate routine, and the generic
+; condes routine in condes.s is not used:
+;
+;   1. Speed. Having several things hardcoded makes it faster. This is
+;      important if it is called in each interrupt.
+;
+;   2. Reentrancy. The condes routines must use self modyfiying code, which
+;      means it is not reentrant. An IRQ using condes, that interrupts
+;      another use of condes will cause unpredicatble behaviour. The current
+;      code avoids this by using locking mechanisms, but it's complex and
+;      has a size and performance penalty.
+;
+; As the normal condes routine, this one has the limitation of 127 table 
+; entries.
+;
+
+               .export callirq
+
+               .import __IRQFUNC_TABLE__, __IRQFUNC_COUNT__
+
+.code
+
+; --------------------------------------------------------------------------
+; Call all IRQ routines. The function needs to use self modifying code and
+; is thereforce placed in the data segment.
+; NOTE: The routine must not be called if the table is empty!
+
+.data
+
+.proc  callirq
+
+        ldy     #.lobyte(__IRQFUNC_COUNT__)
+loop:   dey
+        lda     __IRQFUNC_TABLE__+1,y
+        sta     jmpvec+2                ; Modify code below
+       dey
+        lda     __IRQFUNC_TABLE__+0,y
+        sta     jmpvec+1                ; Modify code below
+               sty     index+1                 ; Modify code below
+jmpvec: jsr            $FFFF                   ; Patched at runtime
+index:         ldy     #$FF                    ; Patched at runtime
+               bne     loop
+        rts
+
+.endproc
+
+

diff --git a/libsrc/runtime/condes.s b/libsrc/runtime/condes.s
index 99c4a6b85d312b5c7e1424e70c538a39061b8a8d..2a2692a7be51bd9f376da21a60eaf63d52d22b5d 100644 (file)
--- a/libsrc/runtime/condes.s
+++ b/libsrc/runtime/condes.s
@@ -52,9 +52,8 @@ exit:   rts
 
 
 ; --------------------------------------------------------------------------
-; 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 ...
+; Generic table call handler. The code uses self modifying code and goes
+; into the data segment for this reason.
 ; NOTE: The routine must not be called if the table is empty!
 
 .data