mirror of
https://github.com/JetSetIlly/Gopher2600.git
synced 2024-06-23 15:03:14 -04:00
298a5d343f
the note about historical versions also being covered wasn't strictly needed and was ugly. the LICENCE being in the root file from the very first commit is sufficient.
51 lines
2.1 KiB
Go
51 lines
2.1 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 patch is used to patch the contents of a cartridge. It works on
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// cartridge memory once a cartridge file has been attached. The package does
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// not implement the patching directly, rather the different cartridge mappers
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// (see cartridge package) deal with that individually.
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//
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// This package simply loads the patch instructions, interprets them and calls
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// the cartridge.Patch() function. Currently only one patch format is
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// supported. This is an ad-hoc format taken from the "In case you can't wait"
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// section of the following web page:
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//
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// "Fixing E.T. The Extra-Terrestrial for the Atari 2600"
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//
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// http://www.neocomputer.org/projects/et/
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//
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// The following extract illustrates the format:
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//
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// -------------------------------------------
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// - E.T. is Not Green
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// -------------------------------------------
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// 17FA: FE FC F8 F8 F8
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// 1DE8: 04
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//
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// Rules:
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//
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// 1. Lines beginning with a hyphen or white space are ignored
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// 2. Offset and values are expressed in hex (case-insensitive)
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// 3. Values and offsets are separated by a colon
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// 4. Multiple values on a line are poked into consecutive offsets, starting
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// from the offset value
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//
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// Note that offsets are expressed with origin zero and have no relationship
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// to how memory is mapped inside the VCS. Imagine that the patches are being
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// applied to the cartridge file image. The cartridge mapper handles the VCS
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// memory side of things.
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package patch
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