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This commit is contained in:
Bill Cox
2014-10-17 11:22:51 -04:00
parent edf556750f
commit d4b8fdae6f
2 changed files with 95 additions and 20 deletions
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66
software/healthcheck.c
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@@ -29,6 +29,8 @@ confirmed.
#define INM_MIN_SAMPLE_SIZE 100
#define INM_ACCURACY 1.05
#define INM_MAX_SEQUENCE 5
#define INM_MAX_COUNT (1 << 14)
static uint8_t inmN;
static uint32_t inmPrevBits;
@@ -39,14 +41,16 @@ static double inmK, inmExpectedEntropyPerBit;
// 1/(2^inmNumBitsOfEntropy * inmCurrentProbability).
static uint32_t inmNumBitsOfEntropy;
static double inmCurrentProbability;
static uint64_t inmTotalBits;
static bool inmPrevBit;
// Print the tables of statistics.
static void inmDumpStats(void) {
uint32_t i;
for(i = 0; i < 1 << inmN; i++) {
if(inmOnes[i] > 0 || inmZeros[i] > 0) {
//if(inmOnes[i] > 0 || inmZeros[i] > 0) {
printf("%x ones:%u zeros:%u\n", i, inmOnes[i], inmZeros[i]);
}
//}
}
}
@@ -77,6 +81,8 @@ bool inmHealthCheckerStart(uint8_t N, double K) {
inmOnes = calloc(1u << N, sizeof(uint32_t));
inmZeros = calloc(1u << N, sizeof(uint32_t));
inmExpectedEntropyPerBit = log(K)/log(2.0);
inmTotalBits = 0;
inmPrevBit = false;
if(inmOnes == NULL || inmZeros == NULL) {
inmHealthCheckerStop();
return false;
@@ -95,6 +101,7 @@ static void resetStats(void) {
// This should be called for each bit generated.
bool inmHealthCheckerAddBit(bool bit) {
inmTotalBits++;
if(inmOnes[inmPrevBits] > INM_MIN_SAMPLE_SIZE ||
inmZeros[inmPrevBits] > INM_MIN_SAMPLE_SIZE) {
uint32_t total = inmZeros[inmPrevBits] + inmOnes[inmPrevBits];
@@ -120,9 +127,11 @@ bool inmHealthCheckerAddBit(bool bit) {
} else {
inmZeros[inmPrevBits]++;
}
inmPrevBits = (inmPrevBits << 1) & ((1 << inmN)-1);
if(bit) {
inmPrevBits |= 1;
// Check for max sequence of 0's or 1's.
uint32_t lowBits = inmPrevBits & ((1 << (INM_MAX_SEQUENCE+1))-1);
if(lowBits == 0 || lowBits == ((1 << (INM_MAX_SEQUENCE+1))-1)) {
printf("Maximum sequence of %d 0's or 1's exceeded\n", INM_MAX_SEQUENCE);
return false;
}
//printf("prevBits: %x\n", inmPrevBits);
if(inmNumBitsSampled < 10000) {
@@ -133,14 +142,15 @@ bool inmHealthCheckerAddBit(bool bit) {
resetStats();
return true;
}
if(inmNumBitsOfEntropy > 10000) {
// Check the entropy is in line with expectations
uint32_t expectedEntropy = inmExpectedEntropyPerBit*inmNumBitsCounted;
if(inmNumBitsOfEntropy > expectedEntropy*INM_ACCURACY || inmNumBitsOfEntropy < expectedEntropy/INM_ACCURACY) {
printf("entropy:%u, expected entropy:%u, num bits counted:%u, num bits sampled:%u\n",
inmNumBitsOfEntropy, expectedEntropy, inmNumBitsCounted, inmNumBitsSampled);
return false;
}
if(inmNumBitsSampled == 10000) {
printf("Generated a total of %lu bits to initialize health checker\n", inmTotalBits);
}
// Check the entropy is in line with expectations
uint32_t expectedEntropy = inmExpectedEntropyPerBit*inmNumBitsCounted;
if(inmNumBitsOfEntropy > expectedEntropy*INM_ACCURACY || inmNumBitsOfEntropy < expectedEntropy/INM_ACCURACY) {
printf("entropy:%u, expected entropy:%u, num bits counted:%u, num bits sampled:%u\n",
inmNumBitsOfEntropy, expectedEntropy, inmNumBitsCounted, inmNumBitsSampled);
return false;
}
return true;
}
@@ -212,13 +222,20 @@ static void reduceStatsIfNeeded(void) {
maxValue = ones;
}
}
if(maxValue > (1 << 30)) {
if(maxValue > INM_MAX_COUNT) {
printf("Scaling stats...\n");
for(i = 0; i < (1 << inmN); i++) {
inmZeros[i] >>= 1;
inmOnes[i] >>= 1;
inmZeros[i] = inmZeros[i]*INM_MAX_COUNT/maxValue;
inmOnes[i] = inmOnes[i]*INM_MAX_COUNT/maxValue;
}
}
/*
if(numBitsSampled > 20000) {
inmNumBitsCounted = inmNumBitsCounted*20000/inmNumBitsSampled;
inmNumBitsOfEntropy = inmNumBitsOfEntropy*20000/inmNumBitsSampled;
inmNumBitsSampled = 20000;
}
*/
}
/* This could be built with one opamp for the multiplier, a comparator with
@@ -240,25 +257,34 @@ static inline bool updateA(double *A, double K, double noise) {
}
static inline bool computeRandBit(double *A, double K, double noiseAmplitude) {
inmPrevBits = (inmPrevBits << 1) & ((1 << inmN)-1);
if(inmPrevBit) {
inmPrevBits |= 1;
}
double noise = noiseAmplitude*(((double)rand()/RAND_MAX) - 0.5);
return updateA(A, K, noise);
inmPrevBit = updateA(A, K, noise);
return inmPrevBit;
}
int main() {
//double K = sqrt(2.0);
double K = 1.82;
uint8_t N = 12;
uint8_t N = 7;
inmHealthCheckerStart(N, K);
srand(time(NULL));
double A = (double)rand()/RAND_MAX; // Simulating INM
double noiseAmplitude = 1.0/(1 << 10);
uint32_t i;
for(i = 0; i < 1 << 26; i++) {
for(i = 0; i < 32; i++) {
// Throw away some initial bits.
computeRandBit(&A, K, noiseAmplitude);
}
for(i = 0; i < 1 << 24; i++) {
bool bit = computeRandBit(&A, K, noiseAmplitude);
if(!inmHealthCheckerAddBit(bit)) {
printf("Failed health check!\n");
resetStats();
//return 1;
return 1;
} else if(inmNumBitsCounted > 0 && (inmNumBitsCounted & 0xfffff) == 0) {
printf("Estimated entropy per bit: %f, estimated K: %f\n", inmHealthCheckerEstimateEntropyPerBit(),
inmHealthCheckerEstimateK());