使用ZIP1和ZIP2指令完成。
/**
*@brief only test 4x4
*/
void transpose_neon_4x4(float *src, float *dst) {
asm volatile (
"ldr q0, [%[src]]\n" // a0123
"ldr q1, [%[src], #16]\n" // b0123
"ldr q2, [%[src], #32]\n" // c0123
"ldr q3, [%[src], #48]\n" // d0123
// zip1: get upper half and interleave store
"zip1 v4.4s, v0.4s, v2.4s\n" // a0c0a1c1
"zip1 v5.4s, v1.4s, v3.4s\n" // b0d0b1d1
// zip2: get lower half and interleave
"zip2 v6.4s, v0.4s, v2.4s\n" // a2c2a3c3
"zip2 v7.4s, v1.4s, v3.4s\n" // b2d2b3d3
// transpose part
"zip1 v0.4s, v4.4s, v5.4s\n" // a0b0c0d0
"zip2 v1.4s, v4.4s, v5.4s\n" // a1b1c1d1
"zip1 v2.4s, v6.4s, v7.4s\n" // a2b2c2d2
"zip2 v3.4s, v6.4s, v7.4s\n" // a3b3c3d3
"str q0, [%[dst]]\n"
"str q1, [%[dst], #16]\n"
"str q2, [%[dst], #32]\n"
"str q3, [%[dst], #48]\n"
: [src] "+r" (src),
[dst] "+r" (dst)
:
: "v0", "v1", "v2", "v3",
"v4", "v5", "v6", "v7",
"memory"
);
}
