68hc11: initial lowlevel code

diff --git a/Kernel/lowlevel-68hc11.s b/Kernel/lowlevel-68hc11.s
new file mode 100644 (file)
index 0000000..ce0c6c9
--- /dev/null
+++ b/Kernel/lowlevel-68hc11.s
@@ -0,0 +1,226 @@
+
+       .file "lowlevel-68hc11"
+       .mode mshort
+
+
+       .globl di
+       .globl ei
+       .globl irqrestore
+
+       .globl outnewline
+       .globl outcharhex
+       .globl outchar
+       .globl outstring
+       .globl outx
+       .globl outy
+       .globl outd
+
+       include "platform/kernel.def"
+       include "kernel-hc11.def"
+
+di:
+       tpa             ; return cc codes in D
+       sei
+       rts
+
+ei:
+       cli
+       rts
+
+irqrestore:            ; D holds the return from di where A is the cc
+       tap             ; we trash overflow and carry but they are assumed
+       rts             ; clobbered anyway
+
+
+
+
+
+outnewline:
+       ldab #0x0d
+       bsr outchar
+       ldab #0x0a
+       bra outchar
+
+
+outcharhex:
+       pshb
+       lsrb
+       lsrb
+       lsrb
+       lsrb
+       bsr outnibble
+       pulb
+       pshb
+       bsr outnibble
+       pulb
+       rts
+
+outnibble:
+       andb #0x0F
+       cmpb #0x0A
+       ble outh2
+       addb #0x07
+outh2: addb #0x30
+outchar:
+       psha
+outchar1:
+       ldaa scsr
+       anda #0x80
+       beq outchar1
+       stab scdr
+       pula
+       rts
+
+outstring:
+       ldab ,x
+       beq outsdone
+       bsr outchar
+       inx
+       bra outstring
+
+outx:
+       xgdx
+       pshx            ; actually the old D
+       bsr outcharhex
+       tab
+       bsr outcharhex
+       pulx
+       xgdx
+outsdone:
+       rts
+
+outy:
+       xgdy
+       pshy            ; actually the old D
+       bsr outcharhex
+       tab
+       bsr outcharhex
+       puly
+       xgdy
+       rts
+
+outd:
+       psha
+       pshb
+       bsr outcharhex
+       tab
+       bsr outcharhex
+       pulb
+       pula
+       rts
+
+
+;
+;      This is slightly odder than most platforms. At the point we
+;      are called the arguments should already be in U_foo as we may be
+;      doing a pure bank switch environment and will switch to the kernel
+;      stack before this far call via the EEPROM
+;
+unix_syscall_entry:
+       ldaa #1
+       staa U_DATA__U_INSYS    ; we may want to use udata-> tricks ?
+       jsr map_kernel          ; no-op in pure banked
+       cli
+       jsr unix_syscall
+       sei
+       clr U_DATA__U_INSYS
+       jmp map_process_always  ; no-op in pure banked
+       ; signal processing happens in per platform code in case we are
+       ; pure banked
+       ; Caller must save errno and return value before invoking signal
+       ; processing.
+
+;
+;      May be a trampoline via a far call and bank switch, but not our
+;      problem in this code. We do however assume the caller stack switched
+;      for us to the IRQ stack
+;
+interrupt_handler:
+       ldaa #1
+       staa U_DATA__U_ININTERRUPT
+       jsr map_save
+       jsr map_kernel
+       ldaa #1
+       staa inint
+       jsr platform_interrupt
+       clr inint
+       tst need_resched
+       beq noswitch
+       clr need_resched
+       ; Save the stack pointer across
+       ldd istack_switched_sp
+       std U_DATA__U_SYSCALL_SP
+       lds #kstack_top
+       ldx U_DATA__U_PTAB
+       ldab #P_READY
+       stab P_TAB__P_STATUS_OFFSET,x
+       jsr switchout
+       jsr map_process_always
+       ; caller will switch back to stack in X
+       ldx U_DATA__U_SYSCALL_SP
+       rts
+noswitch:
+       jsr map_restore
+       ldx istack_switched_sp
+       rts                     ; caller will do the final stack flip
+
+nmi_handler:
+       lds #istack_top - 2
+       jsr map_kernel
+       ldx #nmimsg
+       jsr outstring
+       jsr trap_monitor
+
+nmimsg:
+       .ascii "[NMI]"
+       .byte 13,10,0
+
+;
+;      Runs in kernel banking
+;
+dispatch_process_signal:
+       ldab U_DATA__U_CURSIG
+       bne dosig
+       rts
+dosig:
+       clr U_DATA__U_CURSIG
+       clra
+       ldx #U_DATA__U_SIGVEC
+       abx
+       abx
+       ldd ,x
+       jmp sigdispatch         ; platform provides. Calls d on the
+                               ; user bank and stack. If it returns
+                               ; then will go back via
+                               ; dispatch_process_signal
+
+
+;
+;      Illegal instruction trap helper. Should send a signal
+;      
+sigill:
+       rts
+       
+
+;
+;      Support routines (FIXME copy over)
+;
+       .globl ___ashrsi3
+       .globl ___ashlsi3
+       .globl ___lshlhi3
+       .globl ___lshlsi3
+       .globl ___lshrhi3
+       .globl ___lshrsi3
+       .globl ___one_cmplsi2
+       .globl ___mulhi3
+
+
+___ashrsi3:
+___ashlsi3:
+___lshlhi3:
+___lshlsi3:
+___lshrsi3:
+___lshrhi3:
+___one_cmplsi2:
+___mulhi3:
+       rts