From f648c6fdbfc1dba55cfc55728724233716c63dd0 Mon Sep 17 00:00:00 2001
From: Alan Cox <alan@etchedpixels.co.uk>
Date: Sun, 30 Nov 2014 15:08:04 +0000
Subject: [PATCH] z80: add different includes for CMOS/NMOS Z80

---
 Kernel/lowlevel-z80-cmos.s | 20 ++++++++++++++++++++
 Kernel/lowlevel-z80-nmos.s | 26 ++++++++++++++++++++++++++
 Kernel/lowlevel-z80.s      | 32 +++++++++-----------------------
 3 files changed, 55 insertions(+), 23 deletions(-)
 create mode 100644 Kernel/lowlevel-z80-cmos.s
 create mode 100644 Kernel/lowlevel-z80-nmos.s

diff --git a/Kernel/lowlevel-z80-cmos.s b/Kernel/lowlevel-z80-cmos.s
new file mode 100644
index 00000000..4e392041
--- /dev/null
+++ b/Kernel/lowlevel-z80-cmos.s
@@ -0,0 +1,20 @@
+		.area _COMMONMEM
+
+		; IRQ helpers, in common as they may get used by common C
+		; code (and are tiny)
+
+_di:		ld a, i
+		push af
+		pop hl
+		di
+		ret
+
+_irqrestore:	pop hl		; sdcc needs to get register arg passing
+		pop af		; so badly
+		jp po, was_di
+		ei
+		jr irqres_out
+was_di:		di
+irqres_out:	push af
+		jp (hl)
+
diff --git a/Kernel/lowlevel-z80-nmos.s b/Kernel/lowlevel-z80-nmos.s
new file mode 100644
index 00000000..715a7a5f
--- /dev/null
+++ b/Kernel/lowlevel-z80-nmos.s
@@ -0,0 +1,26 @@
+		.area _COMMONMEM
+
+_di:		xor a		; NMOS Z80 bug work around as per CPU manual
+		push af
+		pop af		; clear byte on stack below our usage
+		ld a, i
+		jp pe, was_ei	; P is now IFF2, if irqs on return is safe
+		dec sp		; the CPU may have lied due to an erratum
+		dec sp
+		pop af		; see if anyone pushed a return address
+		and a
+		jr nz, was_ei	; someone did - IRQs were enabled then
+		scf		; disabled
+was_ei:		push af
+		pop hl
+		ret
+
+_irqrestore:	pop hl
+		pop af
+		jr c, was_di
+		ei
+		jr irqres_out
+was_di:		di
+irqres_out:	push af
+		jp (hl)
+
diff --git a/Kernel/lowlevel-z80.s b/Kernel/lowlevel-z80.s
index b90593a9..2893fe0f 100644
--- a/Kernel/lowlevel-z80.s
+++ b/Kernel/lowlevel-z80.s
@@ -430,29 +430,6 @@ nmi_handler:
 
 
 	.area _COMMONMEM
-;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
-
-
-		; IRQ helpers, in common as they may get used by common C
-		; code (and are tiny)
-
-_di:		ld a, i
-		push af
-		pop hl
-		di
-		ret
-
-_irqrestore:	pop hl		; sdcc needs to get register arg passing
-		pop af		; so badly
-		jp po, was_di
-		ei
-		jr irqres_out
-was_di:		di
-irqres_out:	push af
-		jp (hl)
-
-
-
 
 ; outstring: Print the string at (HL) until 0 byte is found
 ; destroys: AF HL
@@ -530,3 +507,12 @@ numeral:add a, #0x30 ; start at '0' (0x30='0')
         call outchar
         ret
 
+;
+;	Pull in the CPU specific workarounds
+;
+
+	.if NMOS_Z80
+	.include "lowlevel-z80-nmos.s"
+	.else
+	.include "lowlevel-z80-cmos.s"
+	.endif
-- 
2.34.1