65c816: fix various bugs in the core code

With the platform bugs also fixed this takes us to the point that we start
running init and begin to make progress until we take an interrupt in user
mode, at which point badness happens

diff --git a/Kernel/lowlevel-65c816.s b/Kernel/lowlevel-65c816.s
index 4be0465..1366596 100644 (file)
--- a/Kernel/lowlevel-65c816.s
+++ b/Kernel/lowlevel-65c816.s
@@ -299,52 +299,72 @@ signal_out:
 ;
 _doexec:
        sta     tmp1
-       stx     tmp1+1
+       stx     tmp1+1          ;       address to execute from
        sei
        stz     _kernel_flag
+
        rep     #$30
        .i16
        .a16
+
        ldx     tmp1            ;       target address
+
        sep     #$20
        .a8
+
        lda     U_DATA__U_PAGE  ;       get our bank
-       clc
-       adc     U_DATA__U_PAGE  ;       two * bank
+       asl     a
        adc     #STACK_BANKOFF  ;       plus offset
        xba                     ;       swap to xx00
        lda     #$FF            ;       stack top is xxff
        tcs                     ;       Set CPU stack at xxFF
+
        rep     #$20
+       .a16
+
        inc                     ;       gives us the DP at xx+100
        pha
        pld
-       ; Split I/D will need to change this logic
-       lda     U_DATA__U_PAGE  ;       our bank
-       jsr     setdp
-       ; We are now on the correct DP and CPU stack
-       ; So fix up the syscall vector
+
+       ;
+       ;       From this point onwards exec is referencing the user DP
+       ;       user S and kernel B (data)
+       ;
+
+       sep     #$20
+       .a8
+
+       ; Fix up the syscall vector
+
        ldy     #syscall_vector
-       sty     syscall
+       sty     syscall         ;       stores into user DP
        ; And the C stack pointer
        ldy     U_DATA__U_ISP
        sty     sp              ;       sp is in DP so we write user version
-       sep     #$30
-       .i8
-       .a8
-       ; Will need to change for split I/D
+
+       ;
+       ;       From here we are entirely referencing user data but kernel
+       ;       code
+       ;
+       ;       (Will need to change for split I/D)
+
        lda     U_DATA__U_PAGE  ;       bank
        pha                     ;       switch to userdata bank
        plb
+
        pha                     ;       stack bank for rtl
-       rep     #$10
-       .i16
+
+       dex                     ;       Points to end of last instruction
+                               ;       for a return
        phx                     ;       Execution address within bank
-       cli
        lda     #0              ;       
        tay                     ;       DP base is 0
-       sep     #$10
+
+       sep     #$30
+       .a8
        .i8
+
+       cli
        rtl
 
 ;

diff --git a/Kernel/usermem_std-65c816.s b/Kernel/usermem_std-65c816.s
index 1d7c36e..d42934e 100644 (file)
--- a/Kernel/usermem_std-65c816.s
+++ b/Kernel/usermem_std-65c816.s
@@ -154,7 +154,7 @@ __uput:
        sta     ptr3
        stx     ptr3+1
        lda     U_DATA__U_PAGE
-       sta     uputpatch+2
+       sta     uputpatch+1
        phb
        .i16
        .a16