RingBuffer<> is now templated with size, buffer is now static.

This commit is contained in:
Adam Ierymenko 2019-03-22 14:39:52 -07:00
parent af3ec000a0
commit d530356055
6 changed files with 95 additions and 247 deletions

View File

@ -123,7 +123,8 @@ public:
_lastComputedThroughputDistCoeff(0.0),
_lastAllocation(0)
{
prepareBuffers();
memset(_ifname, 0, 16);
memset(_addrString, 0, sizeof(_addrString));
}
Path(const int64_t localSocket,const InetAddress &addr) :
@ -155,22 +156,11 @@ public:
_lastComputedThroughputDistCoeff(0.0),
_lastAllocation(0)
{
prepareBuffers();
memset(_ifname, 0, 16);
memset(_addrString, 0, sizeof(_addrString));
_phy->getIfName((PhySocket *)((uintptr_t)_localSocket), _ifname, 16);
}
~Path()
{
delete _throughputSamples;
delete _latencySamples;
delete _packetValiditySamples;
delete _throughputDisturbanceSamples;
_throughputSamples = NULL;
_latencySamples = NULL;
_packetValiditySamples = NULL;
_throughputDisturbanceSamples = NULL;
}
/**
* Called when a packet is received from this remote path, regardless of content
*
@ -216,7 +206,7 @@ public:
else {
_latency = l;
}
_latencySamples->push(l);
_latencySamples.push(l);
}
/**
@ -345,7 +335,7 @@ public:
_inQoSRecords[packetId] = now;
_packetsReceivedSinceLastQoS++;
}
_packetValiditySamples->push(true);
_packetValiditySamples.push(true);
}
}
@ -362,7 +352,7 @@ public:
int64_t timeSinceThroughputEstimate = (now - _lastThroughputEstimation);
if (timeSinceThroughputEstimate >= ZT_PATH_THROUGHPUT_MEASUREMENT_INTERVAL) {
uint64_t throughput = (float)(_bytesAckedSinceLastThroughputEstimation * 8) / ((float)timeSinceThroughputEstimate / (float)1000);
_throughputSamples->push(throughput);
_throughputSamples.push(throughput);
_maxLifetimeThroughput = throughput > _maxLifetimeThroughput ? throughput : _maxLifetimeThroughput;
_lastThroughputEstimation = now;
_bytesAckedSinceLastThroughputEstimation = 0;
@ -564,7 +554,7 @@ public:
* Record an invalid incoming packet. This packet failed MAC/compression/cipher checks and will now
* contribute to a Packet Error Ratio (PER).
*/
inline void recordInvalidPacket() { _packetValiditySamples->push(false); }
inline void recordInvalidPacket() { _packetValiditySamples.push(false); }
/**
* @return A pointer to a cached copy of the address string for this Path (For debugging only)
@ -582,35 +572,43 @@ public:
*
* @param now Current time
*/
inline void processBackgroundPathMeasurements(int64_t now) {
inline void processBackgroundPathMeasurements(const int64_t now)
{
if (now - _lastPathQualityComputeTime > ZT_PATH_QUALITY_COMPUTE_INTERVAL) {
Mutex::Lock _l(_statistics_m);
_lastPathQualityComputeTime = now;
address().toString(_addrString);
_lastComputedMeanLatency = _latencySamples->mean();
_lastComputedPacketDelayVariance = _latencySamples->stddev(); // Similar to "jitter" (SEE: RFC 3393, RFC 4689)
_lastComputedMeanThroughput = (uint64_t)_throughputSamples->mean();
_lastComputedMeanLatency = _latencySamples.mean();
_lastComputedPacketDelayVariance = _latencySamples.stddev(); // Similar to "jitter" (SEE: RFC 3393, RFC 4689)
_lastComputedMeanThroughput = (uint64_t)_throughputSamples.mean();
// If no packet validity samples, assume PER==0
_lastComputedPacketErrorRatio = 1 - (_packetValiditySamples->count() ? _packetValiditySamples->mean() : 1);
_lastComputedPacketErrorRatio = 1 - (_packetValiditySamples.count() ? _packetValiditySamples.mean() : 1);
// Compute path stability
// Normalize measurements with wildly different ranges into a reasonable range
float normalized_pdv = Utils::normalize(_lastComputedPacketDelayVariance, 0, ZT_PATH_MAX_PDV, 0, 10);
float normalized_la = Utils::normalize(_lastComputedMeanLatency, 0, ZT_PATH_MAX_MEAN_LATENCY, 0, 10);
float throughput_cv = _throughputSamples->mean() > 0 ? _throughputSamples->stddev() / _throughputSamples->mean() : 1;
float throughput_cv = _throughputSamples.mean() > 0 ? _throughputSamples.stddev() / _throughputSamples.mean() : 1;
// Form an exponential cutoff and apply contribution weights
float pdv_contrib = exp((-1)*normalized_pdv) * ZT_PATH_CONTRIB_PDV;
float latency_contrib = exp((-1)*normalized_la) * ZT_PATH_CONTRIB_LATENCY;
// Throughput Disturbance Coefficient
float throughput_disturbance_contrib = exp((-1)*throughput_cv) * ZT_PATH_CONTRIB_THROUGHPUT_DISTURBANCE;
_throughputDisturbanceSamples->push(throughput_cv);
_lastComputedThroughputDistCoeff = _throughputDisturbanceSamples->mean();
_throughputDisturbanceSamples.push(throughput_cv);
_lastComputedThroughputDistCoeff = _throughputDisturbanceSamples.mean();
// Obey user-defined ignored contributions
pdv_contrib = ZT_PATH_CONTRIB_PDV > 0.0 ? pdv_contrib : 1;
latency_contrib = ZT_PATH_CONTRIB_LATENCY > 0.0 ? latency_contrib : 1;
throughput_disturbance_contrib = ZT_PATH_CONTRIB_THROUGHPUT_DISTURBANCE > 0.0 ? throughput_disturbance_contrib : 1;
// Stability
_lastComputedStability = pdv_contrib + latency_contrib + throughput_disturbance_contrib;
_lastComputedStability *= 1 - _lastComputedPacketErrorRatio;
// Prevent QoS records from sticking around for too long
std::map<uint64_t,uint64_t>::iterator it = _outQoSRecords.begin();
while (it != _outQoSRecords.end()) {
@ -647,18 +645,6 @@ public:
*/
inline int64_t lastTrustEstablishedPacketReceived() const { return _lastTrustEstablishedPacketReceived; }
/**
* Initialize statistical buffers
*/
inline void prepareBuffers() {
_throughputSamples = new RingBuffer<uint64_t>(ZT_PATH_QUALITY_METRIC_WIN_SZ);
_latencySamples = new RingBuffer<uint32_t>(ZT_PATH_QUALITY_METRIC_WIN_SZ);
_packetValiditySamples = new RingBuffer<bool>(ZT_PATH_QUALITY_METRIC_WIN_SZ);
_throughputDisturbanceSamples = new RingBuffer<float>(ZT_PATH_QUALITY_METRIC_WIN_SZ);
memset(_ifname, 0, 16);
memset(_addrString, 0, sizeof(_addrString));
}
private:
Mutex _statistics_m;
@ -672,9 +658,9 @@ private:
InetAddress::IpScope _ipScope; // memoize this since it's a computed value checked often
AtomicCounter __refCount;
std::map<uint64_t, uint64_t> _outQoSRecords; // id:egress_time
std::map<uint64_t, uint64_t> _inQoSRecords; // id:now
std::map<uint64_t, uint16_t> _inACKRecords; // id:len
std::map<uint64_t,uint64_t> _outQoSRecords; // id:egress_time
std::map<uint64_t,uint64_t> _inQoSRecords; // id:now
std::map<uint64_t,uint16_t> _inACKRecords; // id:len
int64_t _lastAck;
int64_t _lastThroughputEstimation;
@ -702,16 +688,14 @@ private:
float _lastComputedThroughputDistCoeff;
unsigned char _lastAllocation;
// cached human-readable strings for tracing purposes
char _ifname[16];
char _addrString[256];
RingBuffer<uint64_t> *_throughputSamples;
RingBuffer<uint32_t> *_latencySamples;
RingBuffer<bool> *_packetValiditySamples;
RingBuffer<float> *_throughputDisturbanceSamples;
RingBuffer<uint64_t,ZT_PATH_QUALITY_METRIC_WIN_SZ> _throughputSamples;
RingBuffer<uint32_t,ZT_PATH_QUALITY_METRIC_WIN_SZ> _latencySamples;
RingBuffer<bool,ZT_PATH_QUALITY_METRIC_WIN_SZ> _packetValiditySamples;
RingBuffer<float,ZT_PATH_QUALITY_METRIC_WIN_SZ> _throughputDisturbanceSamples;
};
} // namespace ZeroTier

View File

@ -76,7 +76,6 @@ Peer::Peer(const RuntimeEnvironment *renv,const Identity &myIdentity,const Ident
Utils::getSecureRandom(&_freeRandomByte, 1);
if (!myIdentity.agree(peerIdentity,_key,ZT_PEER_SECRET_KEY_LENGTH))
throw ZT_EXCEPTION_INVALID_ARGUMENT;
_pathChoiceHist = new RingBuffer<int>(ZT_MULTIPATH_PROPORTION_WIN_SZ);
}
void Peer::received(
@ -471,7 +470,7 @@ SharedPtr<Path> Peer::getAppropriatePath(int64_t now, bool includeExpired)
if (_paths[i].p) {
if (rf < _paths[i].p->allocation()) {
bestPath = i;
_pathChoiceHist->push(bestPath); // Record which path we chose
_pathChoiceHist.push(bestPath); // Record which path we chose
break;
}
rf -= _paths[i].p->allocation();
@ -500,7 +499,7 @@ char *Peer::interfaceListStr()
float targetAllocation = 1.0 / alivePathCount;
float currentAllocation = 1.0;
if (alivePathCount > 1) {
currentAllocation = (float)_pathChoiceHist->countValue(i) / (float)_pathChoiceHist->count();
currentAllocation = (float)_pathChoiceHist.countValue(i) / (float)_pathChoiceHist.count();
if (fabs(targetAllocation - currentAllocation) > ZT_PATH_IMBALANCE_THRESHOLD) {
imbalanced = true;
}

View File

@ -60,11 +60,7 @@ private:
Peer() {} // disabled to prevent bugs -- should not be constructed uninitialized
public:
~Peer() {
Utils::burn(_key,sizeof(_key));
delete _pathChoiceHist;
_pathChoiceHist = NULL;
}
~Peer() { Utils::burn(_key,sizeof(_key)); }
/**
* Construct a new peer
@ -674,7 +670,7 @@ private:
AtomicCounter __refCount;
RingBuffer<int> *_pathChoiceHist;
RingBuffer<int,ZT_MULTIPATH_PROPORTION_WIN_SZ> _pathChoiceHist;
bool _linkIsBalanced;
bool _linkIsRedundant;

View File

@ -18,115 +18,6 @@ Public domain.
namespace ZeroTier {
#if 0
// "Naive" implementation, which is slower... might still want this on some older
// or weird platforms if the later versions have issues.
static inline void add(unsigned int h[17],const unsigned int c[17])
{
unsigned int j;
unsigned int u;
u = 0;
for (j = 0;j < 17;++j) { u += h[j] + c[j]; h[j] = u & 255; u >>= 8; }
}
static inline void squeeze(unsigned int h[17])
{
unsigned int j;
unsigned int u;
u = 0;
for (j = 0;j < 16;++j) { u += h[j]; h[j] = u & 255; u >>= 8; }
u += h[16]; h[16] = u & 3;
u = 5 * (u >> 2);
for (j = 0;j < 16;++j) { u += h[j]; h[j] = u & 255; u >>= 8; }
u += h[16]; h[16] = u;
}
static const unsigned int minusp[17] = {
5, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 252
} ;
static inline void freeze(unsigned int h[17])
{
unsigned int horig[17];
unsigned int j;
unsigned int negative;
for (j = 0;j < 17;++j) horig[j] = h[j];
add(h,minusp);
negative = -(h[16] >> 7);
for (j = 0;j < 17;++j) h[j] ^= negative & (horig[j] ^ h[j]);
}
static inline void mulmod(unsigned int h[17],const unsigned int r[17])
{
unsigned int hr[17];
unsigned int i;
unsigned int j;
unsigned int u;
for (i = 0;i < 17;++i) {
u = 0;
for (j = 0;j <= i;++j) u += h[j] * r[i - j];
for (j = i + 1;j < 17;++j) u += 320 * h[j] * r[i + 17 - j];
hr[i] = u;
}
for (i = 0;i < 17;++i) h[i] = hr[i];
squeeze(h);
}
static inline int crypto_onetimeauth(unsigned char *out,const unsigned char *in,unsigned long long inlen,const unsigned char *k)
{
unsigned int j;
unsigned int r[17];
unsigned int h[17];
unsigned int c[17];
r[0] = k[0];
r[1] = k[1];
r[2] = k[2];
r[3] = k[3] & 15;
r[4] = k[4] & 252;
r[5] = k[5];
r[6] = k[6];
r[7] = k[7] & 15;
r[8] = k[8] & 252;
r[9] = k[9];
r[10] = k[10];
r[11] = k[11] & 15;
r[12] = k[12] & 252;
r[13] = k[13];
r[14] = k[14];
r[15] = k[15] & 15;
r[16] = 0;
for (j = 0;j < 17;++j) h[j] = 0;
while (inlen > 0) {
for (j = 0;j < 17;++j) c[j] = 0;
for (j = 0;(j < 16) && (j < inlen);++j) c[j] = in[j];
c[j] = 1;
in += j; inlen -= j;
add(h,c);
mulmod(h,r);
}
freeze(h);
for (j = 0;j < 16;++j) c[j] = k[j + 16];
c[16] = 0;
add(h,c);
for (j = 0;j < 16;++j) out[j] = h[j];
return 0;
}
void Poly1305::compute(void *auth,const void *data,unsigned int len,const void *key)
{
crypto_onetimeauth((unsigned char *)auth,(const unsigned char *)data,len,(const unsigned char *)key);
}
#endif
namespace {
typedef struct poly1305_context {
@ -215,8 +106,7 @@ static inline void U64TO8(unsigned char *p, unsigned long long v)
#define U64TO8(p,v) ((*reinterpret_cast<unsigned long long *>(p)) = (v))
#endif
static inline void
poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
static inline void poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
poly1305_state_internal_t *st = (poly1305_state_internal_t *)ctx;
unsigned long long t0,t1;
@ -241,8 +131,7 @@ poly1305_init(poly1305_context *ctx, const unsigned char key[32]) {
st->final = 0;
}
static inline void
poly1305_blocks(poly1305_state_internal_t *st, const unsigned char *m, size_t bytes) {
static inline void poly1305_blocks(poly1305_state_internal_t *st, const unsigned char *m, size_t bytes) {
const unsigned long long hibit = (st->final) ? 0 : ((unsigned long long)1 << 40); /* 1 << 128 */
unsigned long long r0,r1,r2;
unsigned long long s1,s2;
@ -293,8 +182,7 @@ poly1305_blocks(poly1305_state_internal_t *st, const unsigned char *m, size_t by
st->h[2] = h2;
}
static inline void
poly1305_finish(poly1305_context *ctx, unsigned char mac[16]) {
static inline void poly1305_finish(poly1305_context *ctx, unsigned char mac[16]) {
poly1305_state_internal_t *st = (poly1305_state_internal_t *)ctx;
unsigned long long h0,h1,h2,c;
unsigned long long g0,g1,g2;
@ -582,8 +470,7 @@ poly1305_finish(poly1305_context *ctx, unsigned char mac[16]) {
#endif // MSC/GCC or not
static inline void
poly1305_update(poly1305_context *ctx, const unsigned char *m, size_t bytes) {
static inline void poly1305_update(poly1305_context *ctx, const unsigned char *m, size_t bytes) {
poly1305_state_internal_t *st = (poly1305_state_internal_t *)ctx;
size_t i;

View File

@ -47,40 +47,28 @@ namespace ZeroTier {
* to reduce the complexity of code needed to interact with this type of buffer.
*/
template <class T>
template <class T,size_t S>
class RingBuffer
{
private:
T * buf;
size_t size;
T buf[S];
size_t begin;
size_t end;
bool wrap;
public:
/**
* create a RingBuffer with space for up to size elements.
*/
explicit RingBuffer(size_t size)
: size(size),
RingBuffer() :
begin(0),
end(0),
wrap(false)
{
buf = new T[size];
memset(buf, 0, sizeof(T) * size);
}
~RingBuffer()
{
delete [] buf;
memset(buf,0,sizeof(T)*S);
}
/**
* @return A pointer to the underlying buffer
*/
T* get_buf()
inline T *get_buf()
{
return buf + begin;
}
@ -90,17 +78,17 @@ public:
* @param n Number of elements to copy in
* @return Number of elements we copied in
*/
size_t produce(size_t n)
inline size_t produce(size_t n)
{
n = std::min(n, getFree());
if (n == 0) {
return n;
}
const size_t first_chunk = std::min(n, size - end);
end = (end + first_chunk) % size;
const size_t first_chunk = std::min(n, S - end);
end = (end + first_chunk) % S;
if (first_chunk < n) {
const size_t second_chunk = n - first_chunk;
end = (end + second_chunk) % size;
end = (end + second_chunk) % S;
}
if (begin == end) {
wrap = true;
@ -112,17 +100,14 @@ public:
* Fast erase, O(1).
* Merely reset the buffer pointer, doesn't erase contents
*/
void reset()
{
consume(count());
}
inline void reset() { consume(count()); }
/**
* adjust buffer index pointer as if we copied data out
* @param n Number of elements we copied from the buffer
* @return Number of elements actually available from the buffer
*/
size_t consume(size_t n)
inline size_t consume(size_t n)
{
n = std::min(n, count());
if (n == 0) {
@ -131,11 +116,11 @@ public:
if (wrap) {
wrap = false;
}
const size_t first_chunk = std::min(n, size - begin);
begin = (begin + first_chunk) % size;
const size_t first_chunk = std::min(n, S - begin);
begin = (begin + first_chunk) % S;
if (first_chunk < n) {
const size_t second_chunk = n - first_chunk;
begin = (begin + second_chunk) % size;
begin = (begin + second_chunk) % S;
}
return n;
}
@ -144,19 +129,19 @@ public:
* @param data Buffer that is to be written to the ring
* @param n Number of elements to write to the buffer
*/
size_t write(const T * data, size_t n)
inline size_t write(const T * data, size_t n)
{
n = std::min(n, getFree());
if (n == 0) {
return n;
}
const size_t first_chunk = std::min(n, size - end);
const size_t first_chunk = std::min(n, S - end);
memcpy(buf + end, data, first_chunk * sizeof(T));
end = (end + first_chunk) % size;
end = (end + first_chunk) % S;
if (first_chunk < n) {
const size_t second_chunk = n - first_chunk;
memcpy(buf + end, data + first_chunk, second_chunk * sizeof(T));
end = (end + second_chunk) % size;
end = (end + second_chunk) % S;
}
if (begin == end) {
wrap = true;
@ -169,14 +154,14 @@ public:
*
* @param value A single value to be placed in the buffer
*/
void push(const T value)
inline void push(const T value)
{
if (count() == size) {
if (count() == S) {
consume(1);
}
const size_t first_chunk = std::min((size_t)1, size - end);
const size_t first_chunk = std::min((size_t)1, S - end);
*(buf + end) = value;
end = (end + first_chunk) % size;
end = (end + first_chunk) % S;
if (begin == end) {
wrap = true;
}
@ -185,14 +170,14 @@ public:
/**
* @return The most recently pushed element on the buffer
*/
T get_most_recent() { return *(buf + end); }
inline T get_most_recent() { return *(buf + end); }
/**
* @param dest Destination buffer
* @param n Size (in terms of number of elements) of the destination buffer
* @return Number of elements read from the buffer
*/
size_t read(T * dest, size_t n)
inline size_t read(T *dest,size_t n)
{
n = std::min(n, count());
if (n == 0) {
@ -201,13 +186,13 @@ public:
if (wrap) {
wrap = false;
}
const size_t first_chunk = std::min(n, size - begin);
const size_t first_chunk = std::min(n, S - begin);
memcpy(dest, buf + begin, first_chunk * sizeof(T));
begin = (begin + first_chunk) % size;
begin = (begin + first_chunk) % S;
if (first_chunk < n) {
const size_t second_chunk = n - first_chunk;
memcpy(dest + first_chunk, buf + begin, second_chunk * sizeof(T));
begin = (begin + second_chunk) % size;
begin = (begin + second_chunk) % S;
}
return n;
}
@ -217,34 +202,34 @@ public:
*
* @return The number of elements in the buffer
*/
size_t count()
inline size_t count()
{
if (end == begin) {
return wrap ? size : 0;
return wrap ? S : 0;
}
else if (end > begin) {
return end - begin;
}
else {
return size + end - begin;
return S + end - begin;
}
}
/**
* @return The number of slots that are unused in the buffer
*/
size_t getFree() { return size - count(); }
inline size_t getFree() { return S - count(); }
/**
* @return The arithmetic mean of the contents of the buffer
*/
float mean()
inline float mean()
{
size_t iterator = begin;
float subtotal = 0;
size_t curr_cnt = count();
for (size_t i=0; i<curr_cnt; i++) {
iterator = (iterator + size - 1) % curr_cnt;
iterator = (iterator + S - 1) % curr_cnt;
subtotal += (float)*(buf + iterator);
}
return curr_cnt ? subtotal / (float)curr_cnt : 0;
@ -253,14 +238,14 @@ public:
/**
* @return The arithmetic mean of the most recent 'n' elements of the buffer
*/
float mean(size_t n)
inline float mean(size_t n)
{
n = n < size ? n : size;
n = n < S ? n : S;
size_t iterator = begin;
float subtotal = 0;
size_t curr_cnt = count();
for (size_t i=0; i<n; i++) {
iterator = (iterator + size - 1) % curr_cnt;
iterator = (iterator + S - 1) % curr_cnt;
subtotal += (float)*(buf + iterator);
}
return curr_cnt ? subtotal / (float)curr_cnt : 0;
@ -269,39 +254,36 @@ public:
/**
* @return The sample standard deviation of element values
*/
float stddev() { return sqrt(variance()); }
inline float stddev() { return sqrt(variance()); }
/**
* @return The variance of element values
*/
float variance()
inline float variance()
{
size_t iterator = begin;
float cached_mean = mean();
size_t curr_cnt = count();
if (size) {
T sum_of_squared_deviations = 0;
for (size_t i=0; i<curr_cnt; i++) {
iterator = (iterator + size - 1) % curr_cnt;
float deviation = (buf[i] - cached_mean);
sum_of_squared_deviations += (deviation*deviation);
}
float variance = (float)sum_of_squared_deviations / (float)(size - 1);
return variance;
T sum_of_squared_deviations = 0;
for (size_t i=0; i<curr_cnt; i++) {
iterator = (iterator + S - 1) % curr_cnt;
float deviation = (buf[i] - cached_mean);
sum_of_squared_deviations += (deviation*deviation);
}
return 0;
float variance = (float)sum_of_squared_deviations / (float)(S - 1);
return variance;
}
/**
* @return The number of elements of zero value
*/
size_t zeroCount()
inline size_t zeroCount()
{
size_t iterator = begin;
size_t zeros = 0;
size_t curr_cnt = count();
for (size_t i=0; i<curr_cnt; i++) {
iterator = (iterator + size - 1) % curr_cnt;
iterator = (iterator + S - 1) % curr_cnt;
if (*(buf + iterator) == 0) {
zeros++;
}
@ -313,13 +295,13 @@ public:
* @param value Value to match against in buffer
* @return The number of values held in the ring buffer which match a given value
*/
size_t countValue(T value)
inline size_t countValue(T value)
{
size_t iterator = begin;
size_t cnt = 0;
size_t curr_cnt = count();
for (size_t i=0; i<curr_cnt; i++) {
iterator = (iterator + size - 1) % curr_cnt;
iterator = (iterator + S - 1) % curr_cnt;
if (*(buf + iterator) == value) {
cnt++;
}
@ -330,11 +312,11 @@ public:
/**
* Print the contents of the buffer
*/
void dump()
inline void dump()
{
size_t iterator = begin;
for (size_t i=0; i<size; i++) {
iterator = (iterator + size - 1) % size;
for (size_t i=0; i<S; i++) {
iterator = (iterator + S - 1) % S;
if (typeid(T) == typeid(int)) {
//DEBUG_INFO("buf[%2zu]=%2d", iterator, (int)*(buf + iterator));
}

View File

@ -267,10 +267,10 @@ public:
static inline float normalize(float value, int64_t bigMin, int64_t bigMax, int32_t targetMin, int32_t targetMax)
{
int64_t bigSpan = bigMax - bigMin;
int64_t smallSpan = targetMax - targetMin;
float valueScaled = (value - (float)bigMin) / (float)bigSpan;
return (float)targetMin + valueScaled * (float)smallSpan;
int64_t bigSpan = bigMax - bigMin;
int64_t smallSpan = targetMax - targetMin;
float valueScaled = (value - (float)bigMin) / (float)bigSpan;
return (float)targetMin + valueScaled * (float)smallSpan;
}
/**