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OBD:Instance file format: Difference between revisions
→Backwards and garbage data: let's cut to the chase
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Additionally, because the levels were built on Intel-based machines, which use a little-endian architecture, sequences of bytes which represent numbers were written from least-significant to most-significant byte, which is backwards from how we typically write numbers. When Macs, which were big-endian at the time due to their PowerPC architecture, would read these files, they then had to flip each sequence of bytes in memory before they could be understood. | Additionally, because the levels were built on Intel-based machines, which use a little-endian architecture, sequences of bytes which represent numbers were written from least-significant to most-significant byte, which is backwards from how we typically write numbers. When Macs, which were big-endian at the time due to their PowerPC architecture, would read these files, they then had to flip each sequence of bytes in memory before they could be understood. | ||
An exception to this backwards-writing rule is when strings of ASCII characters were written to disk. These are not numbers and thus are not subject to endianness, so they retain their left-to-right order. | An exception to this backwards-writing rule is when strings of ASCII characters were written to disk. These are not numbers and thus are not subject to endianness, so they retain their left-to-right order. However, four-character codes in the data are backwards, such as "13RV", which is meant to be read "VR31". That's because Oni stored them as a 32-bit integer, not a string, and thus they were written to disk in little-endian order. | ||
==File limits== | ==File limits== | ||