38 lines
970 B
Markdown
38 lines
970 B
Markdown
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# Eyepiece: An IPS patcher
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## Usage
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```sh
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eyepiece patch.ips input.file output.file
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```
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## Building
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```sh
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cargo build
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cargo run -- patch.ips in_file out_file
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```
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## Description
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The IPS(24/16) patchfile format is one of the simplest possible patchfile formats.
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It contains no way to identify the correct target file, and cannot insert or remove bytes.
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An IPS file starts with the magic number "PATCH"
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```console
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0000: 50 41 54 43 48 |PATCH|
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```
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Patches are encoded linearly with no padding or alignment, and
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all numeric values are encoded big-endian. Patches cannot have
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a length of b"EOF", as "EOF" marks the end of the patchfile.
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```console
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xxxx: 45 4f 46 |EOF|
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```
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The patchfile matches the following pseudo-grammar
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```console
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IPS = "PATCH" Patch* "EOF"
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Patch = { offset: u24 != "EOF", data: Data }
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Data = { len: u16 != 0, data: [u8; len] }
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| { _: u16 == 0, len: u16, byte: u8 } // Run-length-encoded data
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```
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