From 9d08d82145e5db73a26ad9706b42c7f83c8a2347 Mon Sep 17 00:00:00 2001
From: yamatcha <sojusojuonetmrlarcbz@gmail.com>
Date: Mon, 15 Jun 2020 01:56:41 +0900
Subject: [PATCH] add: Implement simple BIOS

---
 emulator/bios.go        | 37 +++++++++++++++++++++++++++++++++++++
 emulator/emulator.go    |  4 +++-
 emulator/instruction.go | 15 +++++++++++++++
 3 files changed, 55 insertions(+), 1 deletion(-)
 create mode 100644 emulator/bios.go

diff --git a/emulator/bios.go b/emulator/bios.go
new file mode 100644
index 0000000..5c171db
--- /dev/null
+++ b/emulator/bios.go
@@ -0,0 +1,37 @@
+package emulator
+
+import "fmt"
+
+var biosToTerminal []int = []int{
+	30, 34, 32, 36, 31, 35, 33, 37}
+
+func putString(s string) {
+	for _, i := range s {
+		ioOut8(0x03f8, uint8(i))
+	}
+}
+
+func biosVideoTeletype(emu *Emulator) {
+	color := emu.Registers.getRegister8(BL) & 0x0f
+	ch := emu.Registers.getRegister8(AL)
+	var buf string
+	var bright int
+	terminalColor := biosToTerminal[color&0x07]
+	if color&0x08 == 1 {
+		bright = 1
+	} else {
+		bright = 0
+	}
+	buf = fmt.Sprintf("\x1b[%d;%dm%c\x1b[0m", bright, terminalColor, ch)
+	putString(buf)
+}
+
+func biosVideo(emu *Emulator) {
+	function := emu.Registers.getRegister8(AH)
+	switch function {
+	case 0x0e:
+		biosVideoTeletype(emu)
+	default:
+		fmt.Printf("not implemented BIOS video function 0x%02x\n", function)
+	}
+}
diff --git a/emulator/emulator.go b/emulator/emulator.go
index c8abf3b..30a8c04 100644
--- a/emulator/emulator.go
+++ b/emulator/emulator.go
@@ -6,6 +6,8 @@ const (
 	RegistersCount        = 8
 	MemorySize            = 1024 * 1024
 	AL                    = 0
+	BL                    = 3
+	AH                    = 4
 	EAX                   = 0
 	EDX                   = 2
 	ESP                   = 4
@@ -104,7 +106,7 @@ func (reg *Registers) setRegister8(index byte, value byte) {
 		r := reg.GetRegister32(index) & 0xffffff00
 		reg.setRegister32(index, r|uint32(value))
 	} else {
-		r := reg.GetRegister32(index-4) & 0xffffff00
+		r := reg.GetRegister32(index-4) & 0xffff00ff
 		reg.setRegister32(index-4, r|uint32(value)<<8)
 	}
 }
diff --git a/emulator/instruction.go b/emulator/instruction.go
index a642071..d1939ac 100644
--- a/emulator/instruction.go
+++ b/emulator/instruction.go
@@ -307,6 +307,17 @@ func outDxAl(emu *Emulator) {
 	emu.Eip++
 }
 
+func swi(emu *Emulator) {
+	intIndex := GetCode8(emu, 1)
+	emu.Eip += 2
+	switch intIndex {
+	case 0x10:
+		biosVideo(emu)
+	default:
+		fmt.Printf("unknown interrupt: 0x%02x\n", intIndex)
+	}
+}
+
 func Instructions(index byte) (func(emu *Emulator), error) {
 	switch {
 	case 0x01 == index:
@@ -369,6 +380,10 @@ func Instructions(index byte) (func(emu *Emulator), error) {
 		return movRm32Imm32, nil
 	case 0xc9 == index:
 		return leave, nil
+
+	case 0xcd == index:
+		return swi, nil
+
 	case 0xe8 == index:
 		return callRel32, nil
 	case 0xe9 == index: