如何使用neon将数据类型uint8_t的变量转换为int32_t？我找不到做这件事的内在原因。
最佳答案
假设要将16 x 8位整数的向量转换为4 x 32位整数的向量，可以先将其解压缩为16位，然后再解压缩为32位：
// load 8 bit vector
uint8x16_t v = vld1q_u8(p); // load vector of 16 x 8 bits ints from p
// unpack to 16 bits
int16x8_t vl = vreinterpretq_s16_u16(vmovl_u8(vget_low_u8(v))); // 0..7
int16x8_t vh = vreinterpretq_s16_u16(vmovl_u8(vget_high_u8(v))); // 8..15
// unpack to 32 bits
int32x4_t vll = vmovl_s16(vget_low_s16(vl)); // 0..3
int32x4_t vlh = vmovl_s16(vget_high_s16(vl)); // 4..7
int32x4_t vhl = vmovl_s16(vget_low_s16(vh)); // 8..11
int32x4_t vhh = vmovl_s16(vget_high_s16(vh)); // 12..15