From fb8592dc5eee87112fdb8a669aab52dda2eecf32 Mon Sep 17 00:00:00 2001
From: FeralChild64 <you@example.com>
Date: Sun, 31 Jan 2021 10:27:45 +0100
Subject: [PATCH] several Z80 fixes

---
 src/zvm_m65/debug.s                |  9 +++++++--
 src/zvm_m65/z80_instr_general.s    |  3 ++-
 src/zvm_m65/z80_instr_jump.s       |  5 ++---
 src/zvm_m65/z80_instr_load_16bit.s |  2 +-
 src/zvm_m65/zvm_cpmemu.s           | 13 +++++++++----
 src/zvm_m65/zvm_cputest.s          | 15 +++++++++++++--
 6 files changed, 34 insertions(+), 13 deletions(-)

diff --git a/src/zvm_m65/debug.s b/src/zvm_m65/debug.s
index 64b81deb..2f09c143 100644
--- a/src/zvm_m65/debug.s
+++ b/src/zvm_m65/debug.s
@@ -2,6 +2,8 @@
 
 DBG_print_PC_opcode:
 
+	rts ; XXX disable this to turn debugging on
+
 	php
 	pha
 	phx
@@ -11,7 +13,7 @@ DBG_print_PC_opcode:
 	pha
 
 	jsr PRIMM
-	!pet $0D, "PC: ", 0
+	!pet $0D, $1E, "PC: ", 0
 
 	dew REG_PC
 	lda REG_PC+1
@@ -24,8 +26,11 @@ DBG_print_PC_opcode:
 	!pet " opcode: ", 0
 
 	pla
-	+beq MONITOR
+	pha
 	jsr DBGINT_print_hex_byte
+	pla
+@1:
+	beq @1 ; XXX stop on NOP
 
 	; FALLTROUGH
 
diff --git a/src/zvm_m65/z80_instr_general.s b/src/zvm_m65/z80_instr_general.s
index 4ab50531..31a0387d 100644
--- a/src/zvm_m65/z80_instr_general.s
+++ b/src/zvm_m65/z80_instr_general.s
@@ -103,7 +103,8 @@ Z80_instr_76:                                                                  ;
 	cmp  #$FF                ; $FF = CP/M call
 	+beq zvm_CPMemu
 
-	inc $D021
+@halt: ; XXX temporary, as the BIOS is not ready yet
+	bra @halt
 
 	ldx #$01                 ; default routine, warm boot
 
diff --git a/src/zvm_m65/z80_instr_jump.s b/src/zvm_m65/z80_instr_jump.s
index bd2ef756..d0c2e3a7 100644
--- a/src/zvm_m65/z80_instr_jump.s
+++ b/src/zvm_m65/z80_instr_jump.s
@@ -7,10 +7,9 @@
 Z80_instr_C3:      ; JP nn
 
 	+Z80_FETCH_VIA_PC_INC
-	jsr DBG_print_hex
-	sta REG_PC+0
+	tax
 	+Z80_FETCH_VIA_PC_INC
-	jsr DBG_print_hex
+	stx REG_PC+0
 	sta REG_PC+1
 	jmp ZVM_next
 
diff --git a/src/zvm_m65/z80_instr_load_16bit.s b/src/zvm_m65/z80_instr_load_16bit.s
index c7a6c335..5b5eee2e 100644
--- a/src/zvm_m65/z80_instr_load_16bit.s
+++ b/src/zvm_m65/z80_instr_load_16bit.s
@@ -22,7 +22,7 @@ Z80_instr_FD_21:   +Z80_LD_REGnn_nn REG_IY                                     ;
 !macro Z80_LD_REGnn_REGnn .REGnn1, .REGnn2 {
 	lda .REGnn2+0
 	sta .REGnn1+0
-	jsr .REGnn2+1
+	lda .REGnn2+1
 	sta .REGnn1+1
 	jmp ZVM_next
 }
diff --git a/src/zvm_m65/zvm_cpmemu.s b/src/zvm_m65/zvm_cpmemu.s
index 4a17bbe5..168a105d 100644
--- a/src/zvm_m65/zvm_cpmemu.s
+++ b/src/zvm_m65/zvm_cpmemu.s
@@ -6,12 +6,11 @@
 
 zvm_CPMemu:
 
-	jsr PRIMM
-	!pet "DBG: CP1", $0D, 0
-
 	ldx REG_C
 	cpx #$09
 	beq zvm_CPMemu_09
+	cpx #$02
+	beq zvm_CPMemu_02
 
 	; XXX implement additional functions if needed
 
@@ -21,10 +20,16 @@ zvm_CPMemu_end:
 
 	jmp Z80_instr_C9         ; RET
 
+zvm_CPMemu_02:               ; C_WRITE
+
+	lda REG_E
+	jsr CHROUT
+	bra zvm_CPMemu_end
+
 zvm_CPMemu_09:               ; C_WRITESTR
 
 	+Z80_FETCH_VIA_DE
-	cmp #'$'
+	cmp #$24                 ; CP/M string termination character
 	beq zvm_CPMemu_end
 
 	jsr CHROUT
diff --git a/src/zvm_m65/zvm_cputest.s b/src/zvm_m65/zvm_cputest.s
index f69056f3..407c449f 100644
--- a/src/zvm_m65/zvm_cputest.s
+++ b/src/zvm_m65/zvm_cputest.s
@@ -111,12 +111,12 @@ ZVM_cputest:
 
 	; Copy up to 512 bytes from buffer to target memory
 
-	inw BIOS_LOADCOUNT
+	inw BIOS_LOADCOUNT                           ; XXX workaround for DEW not handling N flag
 
 @loop3:
 
 	dew BIOS_LOADCOUNT
-	beq @loop2 ; XXX why no BMI, without INW?
+	beq @loop2
 
 	lda [BIOS_IOBUFERPTR],z
 	sta [BIOS_LOADPTR],z
@@ -152,8 +152,19 @@ ZVM_cputest:
 	lda #$FF
 	sta [BIOS_LOADPTR],z                         ; $FF = CP/M simulation for CPU test
 
+	lda #$00
+	sta BIOS_LOADPTR+0
+	lda #$76                                     ; HALT
+	sta [BIOS_LOADPTR],z
+	inc BIOS_LOADPTR
+	lda #$FE
+	sta [BIOS_LOADPTR],z                         ; $FE = dummy
+
 	; Run the software
 
+	jsr PRIMM
+	!pet $0D, $0D, 0
+
 	ldz #$00                                     ; in case hypervisor modified it
 	jmp ZVM_next