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AP_Common: use template parameter in bitmask functions 

Substantially improves code optimization and reduces memory usage.
This commit is contained in:
Thomas Watson 2024-07-07 15:16:22 -05:00 committed by Andrew Tridgell
parent 6a4520e8fd
commit 1249388f23
1 changed files with 18 additions and 20 deletions
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38
libraries/AP_Common/Bitmask.h
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@ -23,28 +23,28 @@
#include <AP_InternalError/AP_InternalError.h> #include <AP_InternalError/AP_InternalError.h>
template<uint16_t num_bits> template<uint16_t NUMBITS>
class Bitmask { class Bitmask {
static_assert(num_bits > 0, "must store something"); static constexpr uint16_t NUMWORDS = ((NUMBITS+31)/32);
static_assert(NUMBITS > 0, "must store something");
// for first_set()'s return value // for first_set()'s return value
static_assert(num_bits <= INT16_MAX, "must fit in int16_t"); static_assert(NUMBITS <= INT16_MAX, "must fit in int16_t");
// so that 1U << bits is in range // so that 1U << bits is in range
static_assert(sizeof(unsigned int) >= sizeof(uint32_t), "int too small"); static_assert(sizeof(unsigned int) >= sizeof(uint32_t), "int too small");
public: public:
Bitmask() : Bitmask() {
numbits(num_bits),
numwords((num_bits+31)/32) {
clearall(); clearall();
} }
Bitmask &operator=(const Bitmask&other) { Bitmask &operator=(const Bitmask&other) {
memcpy(bits, other.bits, sizeof(bits[0])*numwords); memcpy(bits, other.bits, sizeof(bits[0])*NUMWORDS);
return *this; return *this;
} }
bool operator==(const Bitmask&other) { bool operator==(const Bitmask&other) {
return memcmp(bits, other.bits, sizeof(bits[0])*numwords) == 0; return memcmp(bits, other.bits, sizeof(bits[0])*NUMWORDS) == 0;
} }
bool operator!=(const Bitmask&other) { bool operator!=(const Bitmask&other) {
@ -66,13 +66,13 @@ public:
// set all bits // set all bits
void setall(void) { void setall(void) {
// set all words to 111... // set all words to 111...
for (uint16_t i=0; i<numwords; i++) { for (uint16_t i=0; i<NUMWORDS; i++) {
bits[i] = 0xffffffff; bits[i] = 0xffffffff;
} }
// ensure out-of-range bits in the last word, if any exist, are 0 // ensure out-of-range bits in the last word, if any exist, are 0
uint16_t num_valid_bits = numbits % 32; uint16_t num_valid_bits = NUMBITS % 32;
if (num_valid_bits) { // word has out of range bits if (num_valid_bits) { // word has out of range bits
bits[numwords-1] = (1U << num_valid_bits) - 1; bits[NUMWORDS-1] = (1U << num_valid_bits) - 1;
} }
} }
@ -97,7 +97,7 @@ public:
// clear all bits // clear all bits
void clearall(void) { void clearall(void) {
memset(bits, 0, numwords*sizeof(bits[0])); memset(bits, 0, NUMWORDS*sizeof(bits[0]));
} }
// return true if given bitnumber is set // return true if given bitnumber is set
@ -112,7 +112,7 @@ public:
// return true if all bits are clear // return true if all bits are clear
bool empty(void) const { bool empty(void) const {
for (uint16_t i=0; i<numwords; i++) { for (uint16_t i=0; i<NUMWORDS; i++) {
if (bits[i] != 0) { if (bits[i] != 0) {
return false; return false;
} }
@ -123,7 +123,7 @@ public:
// return number of bits set // return number of bits set
uint16_t count() const { uint16_t count() const {
uint16_t sum = 0; uint16_t sum = 0;
for (uint16_t i=0; i<numwords; i++) { for (uint16_t i=0; i<NUMWORDS; i++) {
sum += __builtin_popcount(bits[i]); sum += __builtin_popcount(bits[i]);
} }
return sum; return sum;
@ -131,7 +131,7 @@ public:
// return first bit set, or -1 if none set // return first bit set, or -1 if none set
int16_t first_set() const { int16_t first_set() const {
for (uint16_t i=0; i<numwords; i++) { for (uint16_t i=0; i<NUMWORDS; i++) {
if (bits[i] != 0) { if (bits[i] != 0) {
return i*32 + __builtin_ffs(bits[i]) - 1; return i*32 + __builtin_ffs(bits[i]) - 1;
} }
@ -141,19 +141,17 @@ public:
// return number of bits available // return number of bits available
uint16_t size() const { uint16_t size() const {
return numbits; return NUMBITS;
} }
private: private:
bool validate(uint16_t bit) const { bool validate(uint16_t bit) const {
if (bit >= numbits) { if (bit >= NUMBITS) {
INTERNAL_ERROR(AP_InternalError::error_t::bitmask_range); INTERNAL_ERROR(AP_InternalError::error_t::bitmask_range);
return false; return false;
} }
return true; return true;
} }
uint16_t numbits; uint32_t bits[NUMWORDS];
uint16_t numwords;
uint32_t bits[(num_bits+31)/32];
}; };