如何使用 x86 SIMD 有效地将 8 位位图转换为 0/1 整数数组 [英] How to efficiently convert an 8-bit bitmap to array of 0/1 integers with x86 SIMD
问题描述
我想将 8 位整数转换为大小为 8 的数组,每个值都包含一个整数的位值.
I want to convert 8 bit integer to an array of size 8 with each value containing the bit value of an integer.
例如:我有 int8_t x = 8;
我想把它转换成 int8_t array_x = {0,0,0,0,1,0,0,0};
For example: I have int8_t x = 8;
I want to convert this to int8_t array_x = {0,0,0,0,1,0,0,0};
这必须有效地完成,因为此计算是信号处理块的一部分.有没有一种有效的方法来做到这一点?我确实检查了混合说明.当数组元素大小为 8 位时,它不符合我的要求.开发平台为AMD Ryzen.
This has to be done efficiently, since this calculation is part of signal processing block. Is there a efficient way to do this? I did check the blend the instruction. It didn't suit my requirement when having array elements of size 8-bit. development platform is AMD Ryzen.
推荐答案
Inverse movemask"用于具有 0x00:0x01
格式结果的单个字节,具有 SIMD 但没有 BMI2.
"Inverse movemask" for a single byte with 0x00:0x01
formatted results, with SIMD but without BMI2.
__m128i v = _mm_set1_epi8(bitmap);
v = _mm_and_si128(v, _mm_set_epi32(0, 0, 0x80402010, 0x08040201));
v = _mm_min_epu8(v, _mm_set1_epi8(1));
_mm_storel_epi64((__m128i*)&array_x[0], v);
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