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#include <stdint.h>
#include "arm64_immenc.h"
#define one (uint64_t)1
// Returns the packed valid-N-imms-immr (1-1-6-6 bits); returns 0 if bitmask is not encodable
int convert_bitmask(uint64_t bitmask) {
if (bitmask == 0 || bitmask == ~0ULL) return 0;
uint64_t size, mask, pat;
for (size = 6; size > 1; --size) {
mask = (one << (1 << (size - 1))) - 1;
pat = bitmask & mask;
if (pat != ((bitmask >> (1 << (size - 1))) & mask)) {
break;
}
}
mask = (size >= 6) ? ~0ULL : ((one << (1 << size)) - 1);
pat = bitmask & mask;
for (uint64_t i = 1; i < 7 - size; ++i) {
uint64_t boff = i * (1 << size);
if (((bitmask >> boff) & mask) != pat) {
return 0;
}
}
int immr = 0;
uint64_t last_bit = one << ((1 << size) - 1);
if (pat & 1) {
while (pat & last_bit) {
pat = ((pat - last_bit) << 1) | 1;
++immr;
}
} else {
immr = 1 << size;
while (!(pat & 1)) {
pat >>= 1;
--immr;
}
}
if (pat & (pat + 1)) return 0;
int to = 1;
while (pat & (one << to)) ++to;
return 0x2000 + ((size == 6) << 12) + ((((0x1E << size) & 0x3F) + (to - 1)) << 6) + immr;
}
#if 0
#include <unordered_set>
int main() {
std::unordered_set<uint64_t> okvals;
uint64_t val;
for (int n = 1; n < 7; ++n) {
int imms0 = ((n == 6) ? 0xC0 : 0x80) + ((0x1E << n) & 0x3F);
for (int nones = 0; nones < (1 << n) - 1; ++nones) {
val = (one << (nones + 1)) - 1;
for (int j = 0; j < 6 - n; ++j) {
val += val << (1 << (n + j));
}
for (int immr = 0; immr < (1 << n); ++immr) {
int exp = ((imms0 + nones) << 6) + immr;
int got = convert_bitmask(val);
if (exp != got) {
printf("0x%016lX: expected %04X, got %04X\n", val, exp, got);
}
okvals.emplace(val);
val = (val >> 1) | ((val & 1) << 63);
}
}
}
#pragma omp parallel for
for (uint64_t i = 1; i < 0xFFFFFFFFFFFFFFFFu; ++i) {
int got = convert_bitmask(i);
if (!!got != (okvals.find(i) != okvals.cend())) {
printf("0x%016lX: expected %s, got %04X\n", i, (!!got ? "non0" : "0000"), got);
}
}
}
#endif
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