Function SimdPrefix

common/emitter/simd.cpp:180–211

------------------------------------------------------------------------ SimdPrefix - If the lower byte of the opcode is 0x38 or 0x3a, then the opcode is treated as a 16 bit value (in SSE 0x38 and 0x3a denote prefixes for extended SSE3/4 instructions). Any other lower value assumes the upper value is 0 and ignored. Non-zero upper bytes, when the lower byte is not the 0x38 or 0x3a prefix, will gen

	// generate an assertion.
	//
	__emitinline void SimdPrefix(u8 prefix, u16 opcode)
	{
		pxAssertMsg(prefix == 0, "REX prefix must be just before the opcode");

		const bool is16BitOpcode = ((opcode & 0xff) == 0x38) || ((opcode & 0xff) == 0x3a);

		// If the lower byte is not a valid prefix and the upper byte is non-zero it
		// means we made a mistake!
		if (!is16BitOpcode)
			pxAssert((opcode >> 8) == 0);

		if (prefix != 0)
		{
			if (is16BitOpcode)
				xWrite32((opcode << 16) | 0x0f00 | prefix);
			else
			{
				xWrite16(0x0f00 | prefix);
				xWrite8(opcode);
			}
		}
		else
		{
			if (is16BitOpcode)
			{
				xWrite8(0x0f);
				xWrite16(opcode);
			}
			else
				xWrite16((opcode << 8) | 0x0f);
		}
	}

	// clang-format off