mirror of
https://github.com/JetSetIlly/Gopher2600.git
synced 2025-04-02 11:02:17 -04:00
393904abcb
- preparation for adding 7800 emulation
cpu (6507) package uncoupled from upstream dependencies
- cpu no longer logs execution of KIL instruction
- randomisation of registers on startup can be handled by the called of
the cpu's Reset() function
- address errors are filtered by an optional IsAddressError() function
in the Memory interface implementation
- Error field removed from execution.Result type
all references to interface{} replaced with any
98 lines
3.6 KiB
Go
98 lines
3.6 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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package execution
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import (
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"fmt"
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"github.com/jetsetilly/gopher2600/hardware/cpu/instructions"
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)
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// Result records the state/result of each instruction executed on the CPU.
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// Including the address it was read from, a reference to the instruction
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// definition, and other execution details.
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//
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// The Result type is updated every cycle during the execution of the emulated
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// CPU. As the execution continues, more information is acquired and detail
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// added to the Result.
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//
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// The Final field indicates whether the last cycle of the instruction has been
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// executed. An instance of Result with a Final value of false can still be
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// used but with the caveat that the information is incomplete. Note that a
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// Defn of nil means the opcode hasn't even been decoded.
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type Result struct {
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// a reference to the instruction definition
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//
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// * this field can be nil and should be checked before referencing. note
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// that we could make this a non-pointer field but we would still need to
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// check if the definition is valid which would require a flag in the
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// Definition type. a pointer check is just as good
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Defn *instructions.Definition
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// the number of bytes read during instruction decode. if this value is
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// less than Defn.Bytes then the instruction has not yet been fully decoded
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ByteCount int
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// the address at which the instruction began
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Address uint16
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// it would be lovely to have a note of which cartridge bank the address is
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// in, but we want to keep the 6507 emulation as non-specific as possible.
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// if you need to know the cartridge bank then you need to get it somehow
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// else.
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// instruction data is the actual instruction data. so, for example, in the
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// case of branch instruction, instruction data is the offset value.
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InstructionData uint16
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// the actual number of cycles taken by the instruction - usually the same
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// as Defn.Cycles but in the case of PageFaults and branches, this value
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// may be different
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Cycles int
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// whether an extra cycle was required because of 8 bit adder overflow
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PageFault bool
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// whether a known buggy code path (in the emulated CPU) was triggered
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CPUBug string
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// whether branch instruction test passed (ie. branched) or not. testing of
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// this field should be used in conjunction with Defn.IsBranch()
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BranchSuccess bool
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// whether this data has been finalised - some fields in this struct will
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// be undefined if Final is false
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Final bool
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}
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// Reset nullifies all members of the Result instance.
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func (r *Result) Reset() {
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r.Defn = nil
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r.ByteCount = 0
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r.Address = 0
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r.InstructionData = 0
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r.Cycles = 0
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r.PageFault = false
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r.CPUBug = ""
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r.Final = false
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}
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// very rough disassembly. it should not be used in preference to the
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// disassembly package if at all possible. none-the-less it is useful for
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// development purposes.
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func (r *Result) String() string {
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return fmt.Sprintf("%04x %s %s %04x", r.Address, r.Defn.Operator, r.Defn.AddressingMode, r.InstructionData)
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}
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