mirror of
https://github.com/JetSetIlly/Gopher2600.git
synced 2024-05-20 13:48:02 -04:00
4007e6fc37
removed unused caching fields. renamed function and interface names related to breakpoints sharing debugger quantum value is atomic for safe reading outside emulation goroutine. moved quantum definitions to govern package simplification of how debugger interfaces with coprocessor debugger/developer
524 lines
14 KiB
Go
524 lines
14 KiB
Go
// This file is part of Gopher2600.
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//
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// Gopher2600 is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// Gopher2600 is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// You should have received a copy of the GNU General Public License
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// along with Gopher2600. If not, see <https://www.gnu.org/licenses/>.
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// breakpoints are used to halt execution when a target is *changed to* a
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// specific value. compare to traps which are used to halt execution when the
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// target *changes from* its current value *to* any other value.
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package debugger
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import (
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"fmt"
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"strconv"
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"strings"
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"github.com/jetsetilly/gopher2600/debugger/terminal"
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"github.com/jetsetilly/gopher2600/debugger/terminal/commandline"
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"github.com/jetsetilly/gopher2600/disassembly"
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"github.com/jetsetilly/gopher2600/hardware/memory/memorymap"
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"github.com/jetsetilly/gopher2600/hardware/television/specification"
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)
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// breakpoints keeps track of all the currently defined breakers.
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type breakpoints struct {
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dbg *Debugger
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// array of breakers are ORed together
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breaks []breaker
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// prepared targets which we use in hasBreak(). we don't want to setup
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// these targets every time hasBreak() is called.
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checkPcBreak *target
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checkBankBreak *target
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}
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// breaker defines a specific break condition.
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type breaker struct {
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target *target
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// the requested value to break on
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value targetValue
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// skipNext indicates that a break success should be skipped or ignored
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// because the target value isn't new. in other words, we only break when
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// the target has changed *to* the value not when it already *is* the value
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//
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// without this we risk the user becoming trapped in a perpetual break
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// condition, which probably isn't what the user wants or expects
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skipNext bool
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// single linked list ANDs breakers together
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next *breaker
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}
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func (bk breaker) String() string {
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s := strings.Builder{}
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s.WriteString(fmt.Sprintf("%s->%s", bk.target.label, bk.target.stringValue(bk.value)))
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n := bk.next
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for n != nil {
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s.WriteString(fmt.Sprintf(" & %s->%s", n.target.label, n.target.stringValue(n.value)))
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n = n.next
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}
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return s.String()
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}
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// compares two breakers for equality. returns true if the two breakers are
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// logically the same.
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func (bk breaker) cmp(ck breaker) bool {
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// count number of nodes
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bn := 0
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b := &bk
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for b != nil {
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bn++
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b = b.next
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}
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cn := 0
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c := &ck
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for c != nil {
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cn++
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c = c.next
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}
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// if counts are different then the comparison has failed
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if cn != bn {
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return false
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}
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// compare all nodes with one another
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b = &bk
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for b != nil {
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c = &ck
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match := false
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for c != nil {
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match = (b.target.label == c.target.label && b.value == c.value)
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if match {
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break // for loop
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}
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c = c.next
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}
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if !match {
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return false
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}
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b = b.next
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}
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return true
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}
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type checkResult int
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const (
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checkMatch checkResult = iota
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checkNoMatch
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checkIgnoredValue
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)
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// check checks the specific break condition with the current value of
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// the break target.
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func (bk *breaker) check() checkResult {
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if bk.target.value() != bk.value {
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bk.skipNext = false
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return checkNoMatch
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}
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// target value matches break value but it hasn't changed since the
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// previous check. we don't want to break if this is true
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if bk.skipNext {
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return checkIgnoredValue
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}
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if bk.next != nil {
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if bk.next.check() == checkNoMatch {
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return checkNoMatch
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}
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}
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// this is a match. we should skip the next match.
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bk.skipNext = true
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return checkMatch
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}
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// add a new breaker by linking it to the end of an existing breaker.
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func (bk *breaker) add(nbk *breaker) {
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n := bk
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for n.next != nil {
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n = n.next
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}
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n.next = nbk
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}
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// newBreakpoints is the preferred method of initialisation for breakpoints.
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func newBreakpoints(dbg *Debugger) (*breakpoints, error) {
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bp := &breakpoints{dbg: dbg}
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bp.clear()
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var err error
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bp.checkPcBreak, err = parseTarget(bp.dbg, commandline.TokeniseInput("PC"))
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if err != nil {
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return nil, fmt.Errorf("breakpoint: this should not have failed: %w", err)
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}
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bp.checkBankBreak, err = parseTarget(bp.dbg, commandline.TokeniseInput("BANK"))
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if err != nil {
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return nil, fmt.Errorf("breakpoint: this should not have failed: %w", err)
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}
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return bp, err
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}
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// clear all breakpoints.
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func (bp *breakpoints) clear() {
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bp.breaks = make([]breaker, 0, 10)
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}
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// isEmpty returns true if there are no currently defined breakpoints.
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func (bp *breakpoints) isEmpty() bool {
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return len(bp.breaks) == 0
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}
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// drop a specific breakpoint by position in list.
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func (bp *breakpoints) drop(num int) error {
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if len(bp.breaks)-1 < num {
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return fmt.Errorf("breakpoint #%d is not defined", num)
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}
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h := bp.breaks[:num]
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t := bp.breaks[num+1:]
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bp.breaks = make([]breaker, len(h)+len(t), cap(bp.breaks))
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copy(bp.breaks, h)
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copy(bp.breaks[len(h):], t)
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return nil
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}
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// check compares the current state of the emulation with every breakpoint
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// condition. returns a string listing every condition that matches (separated
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// by \n).
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func (bp *breakpoints) check() string {
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if len(bp.breaks) == 0 {
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return ""
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}
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checkString := strings.Builder{}
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for i := range bp.breaks {
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if bp.breaks[i].target.instructionBoundary && !bp.dbg.vcs.CPU.LastResult.Final {
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continue // for loop
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}
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if bp.breaks[i].check() == checkMatch {
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checkString.WriteString(fmt.Sprintf("break on %s\n", bp.breaks[i]))
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}
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}
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return checkString.String()
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}
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// list currently defined breakpoints.
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func (bp breakpoints) list() {
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if len(bp.breaks) == 0 {
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bp.dbg.printLine(terminal.StyleFeedback, "no breakpoints")
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} else {
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bp.dbg.printLine(terminal.StyleFeedback, "breakpoints:")
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for i := range bp.breaks {
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bp.dbg.printLine(terminal.StyleFeedback, "% 2d: %s", i, bp.breaks[i])
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}
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}
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}
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// parse token and add new breakpoint. for example:
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//
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// PC 0xf000
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// adds a new breakpoint to the PC
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//
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// in addition to the description in the HELP file, the breakpoint parser has
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// some additional features which should probably be removed. if only because
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// the commandline template will balk before this function is ever called.
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//
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// for reference though, and very briefly: the | symbol can be used to add more
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// than one condition, instead of calling BREAK more than once.
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//
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// Also, the & symbol can be placed before the target/value combinations.
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// A sort of Polish prefix notation.
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//
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// & SL 100 CL 0 X 10
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//
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// !!TODO: simplify breakpoints parser to match help description.
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func (bp *breakpoints) parseCommand(tokens *commandline.Tokens) error {
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andBreaks := false
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// default target of CPU PC. meaning that "BREAK n" will cause a breakpoint
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// being set on the PC. breaking on PC is probably the most common type of
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// breakpoint. the target will change value when the input string sees
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// something appropriate
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tgt, err := parseTarget(bp.dbg, commandline.TokeniseInput("PC"))
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if err != nil {
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return fmt.Errorf("breakpoint: this should not have failed: %w", err)
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}
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// resolvedTarget keeps track of whether we have specified a target but not
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// given any values for that target. we set it to true initially because
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// we want to be able to change the default target
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resolvedTarget := true
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// we don't add new breakpoints to the main list straight away. we append
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// them to newBreaks first and then check that we aren't adding duplicates
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newBreaks := make([]breaker, 0, 10)
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// whether to add a bank condition to a singular PC BREAK target
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addBankCondition := true
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// loop over tokens:
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// - if token is a valid type value then add the breakpoint for the current target
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// - if it is not a valid type value, try to change the target
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tok, present := tokens.Get()
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for present {
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var val interface{}
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var err error
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// try to interpret the token depending on the type of value the target
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// expects
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switch tgt.value().(type) {
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case string:
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// if token is string type then make it uppercase for now
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val = strings.ToUpper(tok)
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case int:
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var v int64
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v, err = strconv.ParseInt(tok, 0, 32)
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if err == nil {
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val = int(v)
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} else {
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// !!TODO: allow symbol lookup for targets with integer values
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err = fmt.Errorf("invalid value (%s) for target (%s)", tok, tgt.label)
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}
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case bool:
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switch strings.ToLower(tok) {
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case "true":
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val = true
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case "false":
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val = false
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default:
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err = fmt.Errorf("invalid value (%s) for target (%s)", tok, tgt.label)
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}
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default:
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return fmt.Errorf("unsupported value type (%T) for target (%s)", tgt.value(), tgt.label)
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}
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if err == nil {
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// special handling for some targets
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switch tgt.label {
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case "PC":
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ai := bp.dbg.dbgmem.GetAddressInfo(uint16(val.(int)), true)
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val = int(ai.MappedAddress)
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// unusual case but if PC break is not in cartridge area we
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// don't want to add a bank condition
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addBankCondition = addBankCondition && ai.Area == memorymap.Cartridge
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case "Scanline":
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if val.(int) < 0 {
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return fmt.Errorf("scanline value must be greater than or equal to 0")
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}
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if val.(int) > specification.AbsoluteMaxScanlines {
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return fmt.Errorf("scanline value must be less than or equal to %d", specification.AbsoluteMaxScanlines)
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}
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case "Clock":
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if val.(int) < -specification.ClksHBlank {
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return fmt.Errorf("clock value must be greater than or equal to %d", -specification.ClksHBlank)
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}
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if val.(int) > specification.ClksVisible {
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return fmt.Errorf("scanline value must be less than or equal to %d", specification.ClksVisible)
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}
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}
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if andBreaks {
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newBreaks[len(newBreaks)-1].add(&breaker{target: tgt, value: val})
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resolvedTarget = true
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} else {
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newBreaks = append(newBreaks, breaker{target: tgt, value: val})
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resolvedTarget = true
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}
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} else {
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// make sure we've not left a previous target dangling without a value
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if !resolvedTarget {
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return fmt.Errorf("%w", err)
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}
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// possibly switch composition mode
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if tok == "&" {
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andBreaks = true
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} else if tok == "|" {
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andBreaks = false
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} else {
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// if PC target has not been explicitly specified then add
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// bank condition
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addBankCondition = addBankCondition && strings.ToUpper(tok) != "PC"
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// token is not a number or a composition symbol so try to
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// parse a new target
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tokens.Unget()
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tgt, err = parseTarget(bp.dbg, tokens)
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if err != nil {
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return fmt.Errorf("%w", err)
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}
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resolvedTarget = false
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}
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}
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tok, present = tokens.Get()
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}
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if !resolvedTarget {
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// default values
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switch tgt.value().(type) {
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case bool:
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if andBreaks {
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newBreaks[len(newBreaks)-1].add(&breaker{target: tgt, value: true})
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} else {
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newBreaks = append(newBreaks, breaker{target: tgt, value: true})
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}
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default:
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return fmt.Errorf("need a value (%T) to break on (%s)", tgt.value(), tgt.label)
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}
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}
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for _, nb := range newBreaks {
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// if the break is a singular, undecorated PC target then add a BANK
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// condition for the current BANK. this is arguably what the user
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// intends to happen.
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if nb.next == nil && nb.target.label == "PC" && addBankCondition {
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if bp.dbg.vcs.Mem.Cart.NumBanks() > 1 {
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nb.next = &breaker{
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target: bankTarget(bp.dbg),
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value: bp.dbg.vcs.Mem.Cart.GetBank(bp.dbg.vcs.CPU.PC.Address()).Number,
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}
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nb.next.skipNext = true
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}
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}
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if i := bp.checkBreaker(nb); i != noBreakEqualivalent {
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return fmt.Errorf("already exists (%s)", bp.breaks[i])
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}
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bp.breaks = append(bp.breaks, nb)
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}
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return nil
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}
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const noBreakEqualivalent = -1
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// checkBreaker returns the index number of the matching breakpoint. returns
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// noBreakEquivalent if no match is found.
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func (bp *breakpoints) checkBreaker(nb breaker) int {
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for n, ob := range bp.breaks {
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if nb.cmp(ob) {
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return n
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}
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}
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return noBreakEqualivalent
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}
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// HasPCBreak returns true ifan address/bank has a PC breakpoint associated with it.
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func (bp breakpoints) HasPCBreak(addr uint16, bank int) (bool, int) {
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ai := bp.dbg.dbgmem.GetAddressInfo(addr, true)
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check := breaker{
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target: bp.checkPcBreak,
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// casting value to type because that's how the target value is stored
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// for the program counter (see TargetValue() implementation for the
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// ProgramCounter type in the registers package)
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value: int(ai.MappedAddress),
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}
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// we start with the very specific - address and bank
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check.next = &breaker{
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target: bp.checkBankBreak,
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// critical that we cast to int because we'll be comparing against the
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// result of cartridge.GetBank()
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value: bank,
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}
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// check for a breaker for the PC value AND bank value. if
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// checkBreaker() fails then from our point of view, this is a success
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// and we say that the disassembly.Entry has a breakpoint for *this*
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// bank
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if i := bp.checkBreaker(check); i != noBreakEqualivalent {
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return true, i
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}
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// if checkBreaker doesn't report an existing breakpoint, we remove the
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// Bank condition and try again. if checkBreaker fails (success from our
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// point of view) this time, we can say that the disassembly entry has
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// a breakpoint for the program counter only and will break for *any*
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// bank
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check.next = nil
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if i := bp.checkBreaker(check); i != noBreakEqualivalent {
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return true, i
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}
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// there is no breakpoint at that matches this disassembly entry
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return false, noBreakEqualivalent
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}
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func (bp *breakpoints) togglePCBreak(e *disassembly.Entry) {
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has, i := bp.HasPCBreak(e.Result.Address, e.Bank)
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if i != noBreakEqualivalent && has {
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_ = bp.drop(i) // ignoring errors
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return
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}
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// no equivalent breakpoint existed so add one
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ai := bp.dbg.dbgmem.GetAddressInfo(e.Result.Address, true)
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nb := breaker{
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target: bp.checkPcBreak,
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// see above for casting commentary
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value: int(ai.MappedAddress),
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}
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if bp.dbg.vcs.Mem.Cart.NumBanks() > 1 {
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nb.next = &breaker{
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target: bp.checkBankBreak,
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// see above for casting commentary
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value: e.Bank,
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}
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}
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bp.breaks = append(bp.breaks, nb)
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}
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// CheckBreakpoints is a minimal interface to Breakpoints
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type CheckBreakpoints interface {
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HasPCBreak(addr uint16, bank int) (bool, int)
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}
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// GetBreakpoints returns an instance of CheckBreakpoints. This is good for
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// allowing other goroutines access to a read-only copy of the list of
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// breakpoints.
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func (dbg *Debugger) GetBreakpoints() CheckBreakpoints {
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bp := *dbg.halting.breakpoints
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bp.breaks = make([]breaker, len(dbg.halting.breakpoints.breaks))
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copy(bp.breaks, dbg.halting.breakpoints.breaks)
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return bp
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}
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