Gopher2600/debugger/deeppoke.go
JetSetIlly cd2a00d4ba logger.Log() and logger.Logf() now require a logger.Permission instance
the logger.Permission interface indicates whether the environment making
the logging request is allowed to create new log entries. the
environment.Environment type satisifies the Permission interface

logger.Allow is provided as a convienient way of indicating the the log
entry should always be created
2024-04-30 11:23:40 +01:00

300 lines
9.7 KiB
Go

// This file is part of Gopher2600.
//
// Gopher2600 is free software: you can redistribute it and/or modify
// it under the terms of the GNU General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// Gopher2600 is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with Gopher2600. If not, see <https://www.gnu.org/licenses/>.
package debugger
import (
"fmt"
"github.com/jetsetilly/gopher2600/debugger/govern"
"github.com/jetsetilly/gopher2600/hardware/cpu/instructions"
"github.com/jetsetilly/gopher2600/hardware/cpu/registers"
"github.com/jetsetilly/gopher2600/hardware/memory"
"github.com/jetsetilly/gopher2600/hardware/memory/memorymap"
"github.com/jetsetilly/gopher2600/logger"
"github.com/jetsetilly/gopher2600/rewind"
)
// PushDeepPoke schedules a deep poke search for the specificed value in the
// address, replacing it with newValue if found. The valueMask will be applied
// to the value for matching and for setting the newValue - unset bits in the
// mask will preserve the corresponding bits in the found value.
func (dbg *Debugger) PushDeepPoke(addr uint16, value uint8, newValue uint8, valueMask uint8, done func()) bool {
// get current state to use as the resume state after the deeppoke and rewind recovery
searchState := dbg.Rewind.GetCurrentState()
doDeepPoke := func() error {
err := dbg.doDeepPoke(searchState, addr, value, newValue, valueMask)
if err != nil {
logger.Logf(logger.Allow, "deeppoke", "%v", err)
}
if done != nil {
done()
}
return nil
}
dbg.PushFunctionImmediate(func() {
dbg.setState(govern.Rewinding, govern.Normal)
dbg.unwindLoop(doDeepPoke)
})
return true
}
// returned by searchDeepPoke() for convenience.
type deepPoking struct {
state *rewind.State
addr uint16
area memorymap.Area
}
func (dbg *Debugger) doDeepPoke(searchState *rewind.State, addr uint16, value uint8, newValue uint8, valueMask uint8) error {
poking, err := dbg.searchDeepPoke(searchState, addr, value, valueMask)
if err != nil {
return err
}
if poking.state == nil {
return nil
}
switch poking.area {
case memorymap.RAM:
// poking RAM requires a rewind.PokeHook. this is so we can poke
// the new value at the correct point rather than from the resume
// state.
pokeHook := func(s *rewind.State) error {
return deepPoke(s.VCS.Mem, poking, newValue, valueMask)
}
// run from found poking.state to the "current state" in the real emulation
err = dbg.Rewind.RunPoke(poking.state, searchState, pokeHook)
if err != nil {
return err
}
case memorymap.Cartridge:
// if we're not poking RAM then we poke the state that we found
// immediately. this is particulatly important for cartridges with
// multiple banks because we need to poke the bank we found.
err := deepPoke(poking.state.VCS.Mem, poking, newValue, valueMask)
if err != nil {
return err
}
// run from found poking.state to the "current state" in the real emulation
err = dbg.Rewind.RunPoke(poking.state, searchState, nil)
if err != nil {
return err
}
}
return nil
}
// searchDeepPoke looks for the literal value that is being poked into the quoted
// address. Once found the newValue is poked in appropriately.
//
// The valueMask is used during the rewind history search to help decide if the
// value being written matches the value we're looking for. See SearchMemoryWrite()
// and SearchRegisterWrite() in the rewind package.
func (dbg *Debugger) searchDeepPoke(searchState *rewind.State, searchAddr uint16, value uint8, valueMask uint8) (deepPoking, error) {
var poking deepPoking
var err error
const maxSearchDepth = 10
// trace memory write as far back as we can
for depth := 0; depth < maxSearchDepth; depth++ {
searchState, err = dbg.Rewind.SearchMemoryWrite(searchState, searchAddr, value, valueMask)
if err != nil {
return deepPoking{}, err
}
if searchState == nil {
return poking, nil
}
// writes to memory always use a register as the source of the write
var reg rune
switch searchState.VCS.CPU.LastResult.Defn.Operator {
case instructions.Sta:
reg = 'A'
case instructions.Stx:
reg = 'X'
case instructions.Sty:
reg = 'Y'
default:
return deepPoking{}, fmt.Errorf("unexpected write sequence (%s)", searchState.VCS.CPU.LastResult.String())
}
searchState, err = dbg.Rewind.SearchRegisterWrite(searchState, reg, value, valueMask)
if err != nil {
return deepPoking{}, err
}
if searchState == nil {
return poking, nil
}
if searchState.VCS.CPU.LastResult.Defn == nil {
return deepPoking{}, fmt.Errorf("unexpected CPU result with a nil definition")
}
// writes to a register can happen from another register, and immediate
// value, or an address in memory (most probably from the cartridge or
// VCS RAM)
switch searchState.VCS.CPU.LastResult.Defn.AddressingMode {
case instructions.Immediate:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.Address, false)
switch area {
case memorymap.Cartridge:
pc := registers.NewProgramCounter(ma)
pc.Add(1)
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
return poking, nil
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM/Cartridge space (%s)", area)
}
case instructions.AbsoluteIndexedX:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.InstructionData, false)
switch area {
case memorymap.Cartridge:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.X.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
return poking, nil
case memorymap.RAM:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.X.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM/Cartridge space (%s)", area)
}
case instructions.AbsoluteIndexedY:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.InstructionData, false)
switch area {
case memorymap.Cartridge:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.Y.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
return poking, nil
case memorymap.RAM:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.Y.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM/Cartridge space (%s)", area)
}
case instructions.ZeroPage:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.InstructionData, false)
switch area {
case memorymap.RAM:
poking.addr = ma
poking.state = searchState
poking.area = area
// update the search address and continue with the search
searchAddr = poking.addr
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM space (%s)", area)
}
case instructions.ZeroPageIndexedX:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.InstructionData, false)
switch area {
case memorymap.RAM:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.X.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
// update the search address and continue with the search
searchAddr = poking.addr
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM space (%s)", area)
}
case instructions.ZeroPageIndexedY:
ma, area := memorymap.MapAddress(searchState.VCS.CPU.LastResult.InstructionData, false)
switch area {
case memorymap.RAM:
pc := registers.NewProgramCounter(ma)
pc.Add(searchState.VCS.CPU.Y.Address())
poking.addr = pc.Address()
poking.state = searchState
poking.area = area
// update the search address and continue with the search
searchAddr = poking.addr
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM space (%s)", area)
}
case instructions.IndirectIndexed:
pc := registers.NewProgramCounter(searchState.VCS.CPU.LastResult.InstructionData)
lo, err := searchState.VCS.Mem.Read(pc.Address())
if err != nil {
return deepPoking{}, err
}
pc.Add(1)
hi, err := searchState.VCS.Mem.Read(pc.Address())
if err != nil {
return deepPoking{}, err
}
pc.Load((uint16(hi) << 8) | uint16(lo))
pc.Add(searchState.VCS.CPU.Y.Address())
ma, area := memorymap.MapAddress(pc.Address(), false)
switch area {
case memorymap.Cartridge:
poking.addr = ma
poking.state = searchState
poking.area = area
return poking, nil
case memorymap.RAM:
poking.addr = ma
poking.state = searchState
poking.area = area
default:
return deepPoking{}, fmt.Errorf("not deeppoking through non-RAM/Cartridge space (%s)", area)
}
fallthrough
default:
return deepPoking{}, fmt.Errorf("unsupported addressing mode (%s)", searchState.VCS.CPU.LastResult.String())
}
}
return deepPoking{}, fmt.Errorf("deeppoking too deep")
}
// deepPoke changes the bits at the address according the value of valueMask.
func deepPoke(mem *memory.Memory, poke deepPoking, value uint8, valueMask uint8) error {
v, err := mem.Peek(poke.addr)
if err != nil {
return err
}
v = (v & (valueMask ^ 0xff)) | (value & valueMask)
logger.Log(logger.Allow, "deeppoke", fmt.Sprintf("changing %#04x (%s) to %#02x", poke.addr, poke.area, value))
return mem.Poke(poke.addr, v)
}