Trace access to Fred, Jim and Sheila

README.md

@@ -42,13 +42,15 @@ bbz [flags] [filename]
 `filename` is the filename of the ROM to run. With no arguments it
 runs the BBC Basic ROM in `BASIC.ROM`.
 
-Avaliable flags (to put before the ROM filename if present):
+AvaIlable flags (to put before the ROM filename if present):
 
 ``` 
   -M	dump to the console the MOS calls including console I/O calls
   -c	dump to the console the CPU execution operations
   -m	dump to the console the MOS calls excluding console I/O calls
   -p	panic on not implemented MOS calls
+  -s	dump to the console the accesses to Fred, Jim or Sheila
+
 ```
 
 ## Usage example

acornMemory.go

@@ -1,41 +1,86 @@
 package main
 
-import "io/ioutil"
+import (
+	"fmt"
+	"io/ioutil"
+)
+
+type acornMemory struct {
+	data   [65536]uint8
+	memLog bool
+}
 
-// FlatMemory puts RAM on the 64Kb addressable by the processor
-type AcornMemory struct {
-	data [65536]uint8
+func newAcornMemory(memLog bool) *acornMemory {
+	var a acornMemory
+	a.memLog = memLog
+	return &a
 }
 
-// Peek returns the data on the given address
-func (m *AcornMemory) Peek(address uint16) uint8 {
-	return m.data[address]
+func (m *acornMemory) Poke(address uint16, value uint8) {
+	if m.memLog {
+		area := memoryArea(address)
+		if area != "" {
+			fmt.Printf("[[[Poke(%s:%02x, %02x]]]\n", area, address&0xff, value)
+		}
+	}
+
+	m.data[address] = value
 }
 
-// PeekCode returns the data on the given address
-func (m *AcornMemory) PeekCode(address uint16) uint8 {
-	return m.data[address]
+func (m *acornMemory) Peek(address uint16) uint8 {
+	value := m.data[address]
+
+	if m.memLog {
+		area := memoryArea(address)
+		if area != "" {
+			fmt.Printf("[[[Peek(%s:%02x) => %02x]]]\n", area, address&0xff, value)
+		}
+	}
+
+	return value
 }
 
-// Poke sets the data at the given address
-func (m *AcornMemory) Poke(address uint16, value uint8) {
-	m.data[address] = value
+func (m *acornMemory) PeekCode(address uint16) uint8 {
+	return m.Peek(address)
 }
 
-func (m *AcornMemory) loadBinary(filename string) error {
-	bytes, err := ioutil.ReadFile(filename)
+func memoryArea(address uint16) string {
+	switch address >> 8 {
+	case 0xfc:
+		return "FRED"
+	case 0xfd:
+		return "JIM"
+	case 0xfe:
+		return "SHEILA"
+	}
+	return ""
+}
+
+func (m *acornMemory) loadFirmware(firmFilename string) {
+	data, err := ioutil.ReadFile(firmFilename)
 	if err != nil {
-		return err
+		panic(err)
 	}
 
-	for i, v := range bytes {
-		m.Poke(uint16(i), uint8(v))
+	for i := 0; i < len(data); i++ {
+		m.data[i] = data[i]
 	}
+}
 
-	return nil
+func (m *acornMemory) loadRom(filename string) {
+	data, err := ioutil.ReadFile(filename)
+	if err != nil {
+		panic(err)
+	}
+
+	for i := 0; i < len(data); i++ {
+		m.data[romStartAddress+uint16(i)] = data[i]
+	}
 }
 
-func (m *AcornMemory) getString(address uint16, terminator uint8) string {
+// helpers
+
+func (m *acornMemory) getString(address uint16, terminator uint8) string {
 	str := ""
 	for {
 		ch := m.Peek(address)
@@ -49,7 +94,7 @@ func (m *AcornMemory) getString(address uint16, terminator uint8) string {
 	return str
 }
 
-func (m *AcornMemory) storeString(address uint16, s string, terminator uint8, maxLength uint8) {
+func (m *acornMemory) storeString(address uint16, s string, terminator uint8, maxLength uint8) {
 	// maxLength not including terminator
 	var i int
 	for i = 0; i < len(s) && i < int(maxLength); i++ {
@@ -58,32 +103,32 @@ func (m *AcornMemory) storeString(address uint16, s string, terminator uint8, ma
 	m.Poke(address+uint16(i), terminator)
 }
 
-func (m *AcornMemory) getSlice(address uint16, length uint16) []uint8 {
+func (m *acornMemory) getSlice(address uint16, length uint16) []uint8 {
 	slice := make([]uint8, 0, length)
 	for i := uint16(0); i < length; i++ {
 		slice = append(slice, m.Peek(address+i))
 	}
 	return slice
 }
 
-func (m *AcornMemory) storeSlice(address uint16, maxLength uint16, data []uint8) uint16 {
+func (m *acornMemory) storeSlice(address uint16, maxLength uint16, data []uint8) uint16 {
 	var i uint16
 	for i = 0; i < maxLength && i < uint16(len(data)); i++ {
 		m.Poke(address+i, data[i])
 	}
 	return i
 }
 
-func (m *AcornMemory) peekWord(address uint16) uint16 {
+func (m *acornMemory) peekWord(address uint16) uint16 {
 	return uint16(m.Peek(address)) + uint16(m.Peek(address+1))<<8
 }
 
-func (m *AcornMemory) pokeWord(address uint16, value uint16) {
+func (m *acornMemory) pokeWord(address uint16, value uint16) {
 	m.Poke(address, uint8(value&0xff))
 	m.Poke(address+1, uint8(value>>8))
 }
 
-func (m *AcornMemory) peeknbytes(address uint16, n int) uint64 {
+func (m *acornMemory) peeknbytes(address uint16, n int) uint64 {
 	ticks := uint64(0)
 	for i := n - 1; i >= 0; i-- {
 		ticks <<= 8
@@ -92,7 +137,7 @@ func (m *AcornMemory) peeknbytes(address uint16, n int) uint64 {
 	return ticks
 }
 
-func (m *AcornMemory) pokenbytes(address uint16, n int, value uint64) {
+func (m *acornMemory) pokenbytes(address uint16, n int, value uint64) {
 	for i := 0; i < n; i++ {
 		m.Poke(address+uint16(i), uint8(value&0xff))
 		value >>= 8

bbz.go

@@ -11,31 +11,48 @@ import (
 	"github.com/ivanizag/izapple2/core6502"
 )
 
-func RunMOSEnvironment(romFilename string, firmFilename string, cpuLog bool, apiLog bool, apiLogIO bool, panicOnErr bool) {
+/*
+	See:
+		http://www.sprow.co.uk/bbc/library/sidewrom.pdf
+*/
+
+func RunMOSEnvironment(romFilename string, firmFilename string, cpuLog bool, apiLog bool, apiLogIO bool, memLog bool, panicOnErr bool) {
 	// Prepare environment
 	var env environment
 	env.in = bufio.NewScanner(os.Stdin)
 	env.referenceTime = time.Now()
 	env.timer = 0
 	env.lastTimerUpdate = time.Now()
-	env.mem = new(AcornMemory)
+	env.mem = newAcornMemory(memLog)
 	env.cpu = core6502.NewNMOS6502(env.mem)
 	env.cpu.SetTrace(cpuLog)
 	env.vdu = newVdu()
-
-	loadMosFromFile(&env, firmFilename)
-	loadRom(&env, romFilename)
-
 	env.apiLog = apiLog
 	env.apiLogIO = apiLogIO
 	env.panicOnErr = panicOnErr
 
+	env.mem.loadFirmware(firmFilename)
+	env.mem.loadRom(romFilename)
+
+	/*
+		Next, the MOS will set the error point at &FD/&FE to point at the version string (or copyright
+		message if no version string is present).
+	*/
+	copyrightAddress := 0x8000 + 1 + uint16(env.mem.Peek(romCopyrightOffsetPointer))
+	copyrigt := env.mem.getString(copyrightAddress, 0)
+	env.mem.pokeWord(zpErrorPointer, copyrightAddress)
+	/*
+		The MOS also automatically prints the ROM's title string (&8009) so that the user is acknowledged.
+	*/
+	language := env.mem.getString(romTitleString, 0)
+	fmt.Printf("%s - %s\n", language, copyrigt)
+
 	// Execute
 	for !env.stop {
 		env.cpu.ExecuteInstruction()
 
 		pc, sp := env.cpu.GetPCAndSP()
-		if pc >= entryPoints && pc < mosVectors {
+		if pc >= entryPoints && pc <= epEntryPointsLast {
 			a, x, y, p := env.cpu.GetAXYP()
 
 			// Intercept MOS API calls.
@@ -187,7 +204,7 @@ func RunMOSEnvironment(romFilename string, firmFilename string, cpuLog bool, api
 				env.mem.Poke(zpAccumulator, a)
 				env.mem.pokeWord(zpErrorPointer, address)
 				env.cpu.SetAXYP(pStacked&0x10, x, y, p)
-				brkv := env.mem.peekWord(vectorBRKV)
+				brkv := env.mem.peekWord(vectorBRK)
 				env.cpu.SetPC(brkv)
 
 				env.log(fmt.Sprintf("BREAK(ERR=%02x, '%s')", faultNumber, faultString))

constants.go

@@ -0,0 +1,75 @@
+package main
+
+/*
+Memory map, pages:
+	00: zero page
+	01: stack
+	02: mos vectors and other
+	...
+	80: loaded rom
+	...
+	fa: brk error messages
+	fb: entrypoints trapped by the host
+	fc: FRED
+	fd: JIM
+	fe: SHEILA
+	ff: mos and 6502 entrypoints
+
+*/
+const (
+	zpAccumulator  uint16 = 0x00fc
+	zpErrorPointer uint16 = 0x00fd
+
+	vectorBRK uint16 = 0x0202
+
+	// ROM header https://tobylobster.github.io/mos/mos/S-s2.html#SP26
+	userMemBottom             uint16 = 0x0e00
+	romStartAddress           uint16 = 0x8000
+	romServiceEntry           uint16 = 0x8003
+	romTypeByte               uint16 = 0x8006
+	romCopyrightOffsetPointer uint16 = 0x8007
+	romTitleString            uint16 = 0x8009
+
+	// Scratch area for errors in page 0xfa
+	errorArea             uint16 = 0xfa00
+	errorMessageMaxLength int    = 100
+
+	// Entry points for host interception in page 0xfb
+	entryPoints       uint16 = 0xfb00
+	epUPT             uint16 = 0xfb00
+	epEVNT            uint16 = 0xfb01
+	epFSC             uint16 = 0xfb02
+	epFIND            uint16 = 0xfb03
+	epGBPB            uint16 = 0xfb04
+	epBPUT            uint16 = 0xfb05
+	epBGET            uint16 = 0xfb06
+	epARGS            uint16 = 0xfb07
+	epFILE            uint16 = 0xfb08
+	epRDCH            uint16 = 0xfb09
+	epWRCH            uint16 = 0xfb0a
+	epWORD            uint16 = 0xfb0b
+	epBYTE            uint16 = 0xfb0c
+	epCLI             uint16 = 0xfb0d
+	epIRQ2            uint16 = 0xfb0e
+	epIRQ1            uint16 = 0xfb0f
+	epBRK             uint16 = 0xfb10
+	epUSER            uint16 = 0xfb11
+	epSYSBRK          uint16 = 0xfb12
+	epRDRM            uint16 = 0xfb13
+	epVDUCH           uint16 = 0xfb14
+	epGSINIT          uint16 = 0xfb16
+	epGSREAD          uint16 = 0xfb17
+	epNET             uint16 = 0xfb18
+	epVDU             uint16 = 0xfb19
+	epKEY             uint16 = 0xfb1a
+	epINS             uint16 = 0xfb1b
+	epREM             uint16 = 0xfb1c
+	epCNP             uint16 = 0xfb1d
+	epIND1            uint16 = 0xfb1e
+	epIND2            uint16 = 0xfb1f
+	epIND3            uint16 = 0xfb20
+	epEntryPointsLast uint16 = 0xfb20
+
+	maxFiles        = 5
+	errorTodo uint8 = 129 // TODO: find proper error number
+)

environment.go

@@ -11,7 +11,7 @@ import (
 
 type environment struct {
 	cpu *core6502.State
-	mem *AcornMemory
+	mem *acornMemory
 	vdu *vdu
 	in  *bufio.Scanner