From 85e6c3417e78cea25b92b94146a21e8f473ca6f1 Mon Sep 17 00:00:00 2001
From: Ian Burgmyer <spectere@gmail.com>
Date: Mon, 7 Sep 2020 19:57:13 -0400
Subject: [PATCH] Added call/ret CPU test.

---
 Makefile        |  21 ++++++--
 cpu/callRet.asm | 148 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 166 insertions(+), 3 deletions(-)
 create mode 100644 cpu/callRet.asm

diff --git a/Makefile b/Makefile
index bfcb439..2af3e9f 100644
--- a/Makefile
+++ b/Makefile
@@ -9,7 +9,7 @@ MKDIR = mkdir
 
 .PHONY: dirs
 
-all: dirs video
+all: dirs cpu video
 
 clean:
 	rm -r ${BIN_DIR}/ ${OBJ_DIR}/
@@ -18,12 +18,27 @@ dirs:
 	${MKDIR} -p ${BIN_DIR}
 	${MKDIR} -p ${OBJ_DIR}
 
+#
+# CPU
+#
+cpu: cpuDirs \
+	${BIN_DIR}/cpu/callRet.gb
+
+cpuDirs:
+	${MKDIR} -p ${OBJ_DIR}/cpu
+	${MKDIR} -p ${BIN_DIR}/cpu
+
+${BIN_DIR}/cpu/callRet.gb: dirs cpu/callRet.asm
+	${AS} -o ${OBJ_DIR}/cpu/callRet.o cpu/callRet.asm
+	${LD} -o ${BIN_DIR}/cpu/callRet.gb ${OBJ_DIR}/cpu/callRet.o
+	${FIX} ${BIN_DIR}/cpu/callRet.gb
+
 #
 # Video
 #
 video: videoDirs \
-       ${BIN_DIR}/video/lcdToggle.gb \
-       ${BIN_DIR}/video/vblankInt.gb
+    ${BIN_DIR}/video/lcdToggle.gb \
+    ${BIN_DIR}/video/vblankInt.gb
 
 videoDirs:
 	${MKDIR} -p ${BIN_DIR}/video
diff --git a/cpu/callRet.asm b/cpu/callRet.asm
new file mode 100644
index 0000000..dae1abf
--- /dev/null
+++ b/cpu/callRet.asm
@@ -0,0 +1,148 @@
+HeaderTitle EQUS "\"CALLRET\""
+
+include "common/defines.inc"
+include "common/header.inc"
+
+; 1: call    / ret
+; 2: call    / ret nz
+; 3: call    / ret z
+; 4: call    / ret nc
+; 5: call    / ret c
+; 6: call nz / ret
+; 7: call z  / ret
+; 8: call nc / ret
+; 9: call c  / ret
+
+SECTION "home", ROM0
+ProgramStart:
+	call waitVBlank
+
+	; disable the LCD while we clear the logo
+	ld hl, $ff40
+	ld a, [hl]
+	res 7, a
+	ld [hl], a
+	call clearLogo
+
+	; enable the LCD
+	ld hl, $ff40
+	ld a, [hl]
+	set 7, a
+	ld [hl], a
+
+	call waitVBlank
+	ld hl, $8010
+	call drawRect
+
+	call waitVBlank
+	call retNz
+	ld hl, $8040
+	call drawRect
+
+	call waitVBlank
+	call retZ
+	ld hl, $8060
+	call drawRect
+
+	call waitVBlank
+	call retNc
+	ld hl, $8080
+	call drawRect
+
+	call waitVBlank
+	call retC
+	ld hl, $80a0
+	call drawRect
+
+	call waitVBlank
+	ld a, 2
+	dec a
+	ld hl, $8110
+	call nz, drawRect
+
+	call waitVBlank
+	ld a, 1
+	dec a
+	ld hl, $8130
+	call z, drawRect
+
+	call waitVBlank
+	ld a, 2
+	dec a
+	ld hl, $8150
+	call nc, drawRect
+
+	call waitVBlank
+	ld a, 255
+	add a, 1
+	ld hl, $8170
+	call c, drawRect
+
+loop:
+	jr loop
+
+
+SECTION "waitVBlank", ROM0[$200]
+waitVBlank:
+	ldh a, [$ff44]
+	cp $90
+	jr nz, waitVBlank
+	ret
+
+
+SECTION "clearLogo", ROM0[$220]
+clearLogo:
+	ld hl, $81A0
+.clearLoop:
+	ld a, $0
+	ld [hld], a
+	ld a, h
+	cp $80
+	jr nz, .clearLoop
+	ld a, l
+	cp $10
+	jr nz, .clearLoop
+	ret
+
+
+SECTION "drawRect", ROM0[$240]
+drawRect:
+	push af
+	push de
+	ld d, 16
+	ld a, $ff
+.logoDraw:
+	ld [hli], a
+	dec d
+	jr nz, .logoDraw
+	pop de
+	pop af
+	ret
+
+SECTION "ret", ROM0[$300]
+retError:
+	jr retError
+
+retNz:
+	ld a, 2
+	dec a
+	ret nz
+	jr retError
+
+retZ:
+	ld a, 1
+	dec a
+	ret z
+	jr retError
+
+retNc:
+	ld a, 2
+	dec a
+	ret nc
+	jr retError
+
+retC:
+	ld a, 255
+	add a, 1
+	ret c
+	jr retError