Steinar H. Gunderson: Decompilation patterns part 9, sign extension
Today, for something completely different: s.x = (s16) ((s32) (temp_v0 << 0x10) >> 0x11); MIPS has 16-bit loads and stores, but not 16-bit (signed) arithmetic, so if it wants to do that, it needs to sign-extend to 32-bit first.
Executive Summary
Today, for something completely different: s.x = (s16) ((s32) (temp_v0 << 0x10) >> 0x11); MIPS has 16-bit loads and stores, but not 16-bit (signed) arithmetic, so if it wants to do that, it needs to sign-extend to 32-bit first. And it does that by first shifting up by 16 so that the 16-bit sign bit is at the 32-bit sign bit, and then it can do an arithmetic shift afterwards. So what you want is: s16 temp_v0; s.x = temp_v0 >> 1; Sometimes, it can be pretty stubborn, and you'll need to go through memory or similar before GCC really inserts the shift patterns you want.
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