Debug the rs232 routines. This involved using two new segments, STARTUP

and NMI to make sure the NMI handler is loaded into the low 16K of memory
which are active when the control is passed from the ROM NMI stub to the
user handler.

git-svn-id: svn://svn.cc65.org/cc65/trunk@1086 b7a2c559-68d2-44c3-8de9-860c34a00d81

diff --git a/libsrc/c128/c128.inc b/libsrc/c128/c128.inc
index d97abd48c81b2925f2bddffcab7d409fbbad6a4a..8e4415e70792f6171438c0cda40e27c7d78307b4 100644 (file)
--- a/libsrc/c128/c128.inc
+++ b/libsrc/c128/c128.inc
@@ -172,6 +172,7 @@ CIA2_CRB    = $DD0F
 ; I/O: MMU
 
 MMU_CR         = $FF00
+CC65_MMU_CFG   = $0E   ; Bank 0 with kernal ROM
 
 ; ---------------------------------------------------------------------------
 ; Super CPU

diff --git a/libsrc/c128/crt0.s b/libsrc/c128/crt0.s
index a1c97ce76cc3979d89de33133955e404b97482e2..25ec5e6c38933acb0525076a71c2d3c75bbba92a 100644 (file)
--- a/libsrc/c128/crt0.s
+++ b/libsrc/c128/crt0.s
@@ -18,7 +18,6 @@
 ; ------------------------------------------------------------------------
 ; Constants
 
-CC65_MMU_CFG   = $0E   ; Bank 0 with kernal ROM
 IRQInd         = $2FD  ; JMP $0000 - used as indirect IRQ vector
 
 ; ------------------------------------------------------------------------
@@ -45,9 +44,16 @@ tmp3:                .res    1
 tmp4:          .res    1
 regbank:       .res    6       ; 6 byte register bank
 
-zpspace        = * - zpstart           ; Zero page space allocated
+zpspace        = * - zpstart           ; Zero page space allocated
 
-.code
+; Place the startup code in a special segment to cope with the quirks of
+; c128 banking. Do also create an empty segment named "NMI" to avoid
+; warnings if the rs232 routines are not used.
+
+.segment        "NMI"
+; empty
+
+.segment               "STARTUP"
 
 ; ------------------------------------------------------------------------
 ; BASIC header with a SYS call

diff --git a/libsrc/c128/rs232.s b/libsrc/c128/rs232.s
index 5718cba07267d534b9eae6925005f7382a2e6889..0c5d7cf5cde3f1ba5175d8ec969762df822651c9 100644 (file)
--- a/libsrc/c128/rs232.s
+++ b/libsrc/c128/rs232.s
@@ -27,6 +27,8 @@
        .export         _rs232_init, _rs232_params, _rs232_done, _rs232_get
        .export         _rs232_put, _rs232_pause, _rs232_unpause, _rs232_status
 
+       .include        "c128.inc"
+
 
 NmiExit = $ff33     ;exit address for nmi
 
@@ -120,7 +122,7 @@ _rs232_init:
 
 ;** check for super-cpu at 20 MHz
 
-       bit     $d0bc
+       bit     SCPU_Detect
        bmi     @L4
        bit     $d0b8
        bvs     @L4
@@ -142,14 +144,14 @@ _rs232_init:
 
 ;** set up nmi's
 
-       lda     $318
-       ldy     $319
+       lda     NMIVec
+       ldy     NMIVec+1
        sta     NmiSave+0
        sty     NmiSave+1
        lda     #<NmiHandler
        ldy     #>NmiHandler
-       sta     $318
-       sty     $319
+       sta     NMIVec
+       sty     NMIVec+1
 
 ;** set default to 2400-8N1, enable interrupts
 
@@ -313,8 +315,8 @@ _rs232_done:
 
        lda     NmiSave+0
        ldy     NmiSave+1
-       sta     $318
-       sty     $319
+       sta     NMIVec
+       sty     NMIVec+1
 
 ; Flag uninitialized
 
@@ -530,8 +532,17 @@ _rs232_status:
 ; C64  @  57.6k: 177 cycles avail, worstAvail=177-43? = 134
 ; SCPU @ 230.4k: 868 cycles avail: for a joke!
 ;
+; Because of the C128 banking, the NMI handler must go into the non banked
+; memory, since the ROM NMI entry point will switch to a configuration where
+; only the lowest 16K of RAM are visible. We will place the NMI handler into
+; it's own segment and map this segment into the lower 16K in the linker 
+; config.
+  
+.segment       "NMI"
 
 NmiHandler:
+       lda     #CC65_MMU_CFG           ;(2)
+       sta     MMU_CR                  ;(4)
                lda     ACIA+RegStatus          ;(4) ;status ;check for byte received
        and     #$08                    ;(2)
        beq     @L9                     ;(2*)
@@ -553,7 +564,7 @@ NmiHandler:
 ; Assert flow control
 
 @L2:   lda     RtsOff                  ;(3)  ;assert flow control if buffer space too low
-       sta     ACIA+RegCommand ;(4) ;command
+       sta     ACIA+RegCommand         ;(4) ;command
        sta     Stopped                 ;(3)
        jmp     NmiExit                 ;(3)
 
@@ -569,6 +580,9 @@ NmiHandler:
 @L4:           jmp     NmiExit
 
 @L9:   jmp     NmiContinue
+                    
+
+.code
 
 ;----------------------------------------------------------------------------
 ;