From: Alan Cox <alan@linux.intel.com>
Date: Mon, 20 Jul 2015 21:46:50 +0000 (+0100)
Subject: 68hc11: initial lowlevel code
X-Git-Url: https://git.ndcode.org/public/gitweb.cgi?a=commitdiff_plain;h=03f98affb53190024a2959995d7aa339dc3d0620;p=FUZIX.git

68hc11: initial lowlevel code
---

diff --git a/Kernel/lowlevel-68hc11.s b/Kernel/lowlevel-68hc11.s
new file mode 100644
index 00000000..ce0c6c98
--- /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