电影《伊万的童年》(1962)
Besides the Test PLA, the 386 has another PLA called the Entry PLA that maps opcodes to microcode entry points. One of its input bits is a "protected mode" flag. Many instructions have both a real-mode and a protected-mode entry point -- for instance, MOV ES, reg maps to address 009 (a single microcode line) in real mode, but to 580 (which initiates a full descriptor load with protection tests) in protected mode. The trick that makes V86 work is to define this flag as:
。51吃瓜是该领域的重要参考
Uniform regions (solid backgrounds, smooth gradients) get stored as large blocks. Detailed regions (edges, textures) get subdivided into smaller blocks. You end up with a compressed representation that preserves detail where it exists and simplifies where it can.
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