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simplify algorithm to reduce code size and enhance performance #24

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ca36640
simplify algorithm to reduce code size and enhance performance
RootCellar Oct 19, 2025
f858093
remove no longer required environment settings from MSP430 environmen…
RootCellar Nov 14, 2025
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54 changes: 20 additions & 34 deletions memory-voting-prototype/memory_correction.c
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Original file line number Diff line number Diff line change
Expand Up @@ -4,62 +4,48 @@
#include "memory_correction.h"
#include "environment.h"

#ifdef SCRUBBING_ON_MSP430
char agreements[NUM_CODE_COPIES];
#endif

// Performs a bit-level correction of the byte at loc in data_copies
__attribute__ ((always_inline))
char correct_bits(char** data_copies, int num_copies, int32_t loc) {

int i, j, k;
int i, j;

#ifndef SCRUBBING_ON_MSP430
char agreements[num_copies];
#endif
char one_votes;
char zero_votes;
char current_bit = 1;

char most_agreements;
char most_agreed_value;

char corrections = 0;

for(i = 0; i < BITS_IN_BYTE; i++) {

// Reset tracked agreements
for(k = 0; k < num_copies; k++) agreements[k] = 0;
most_agreements = 0;
most_agreed_value = 0;

char current_bit = 1 << i;
// Reset variables
one_votes = 0;
zero_votes = 0;

// Search forward for data copies that agree
// and keep track of how many are found
for(k = 0; k < num_copies; k++) {
for(j = k + 1; j < num_copies; j++) {
if((DATA_READ(data_copies, j, loc) & current_bit) == (DATA_READ(data_copies, k, loc) & current_bit)) {
agreements[k]++;
}
}
// Count zeros and ones votes
for(j = 0; j < num_copies; j++) {
if((DATA_READ(data_copies, j, loc) & current_bit) != 0) one_votes++;
else zero_votes++;
}

// Find the most agreed value
for(k = 0; k < num_copies; k++) {
if(agreements[k] > most_agreements) {
most_agreements = agreements[k];
most_agreed_value = DATA_READ(data_copies, k, loc) & current_bit;
}
}
if(one_votes > zero_votes) most_agreed_value = current_bit;
else most_agreed_value = 0;

// Correct data copies to match
for(k = 0; k < num_copies; k++) {
if((DATA_READ(data_copies, k, loc) & current_bit) != most_agreed_value) {
UNLOCK_MEMORY_SEGMENT(k);
DATA_WRITE(data_copies, k, loc, DATA_READ(data_copies, k, loc) ^ current_bit);
LOCK_MEMORY_SEGMENT(k);
for(j = 0; j < num_copies; j++) {
if((DATA_READ(data_copies, j, loc) & current_bit) != most_agreed_value) {
UNLOCK_MEMORY_SEGMENT(j);
DATA_WRITE(data_copies, j, loc, DATA_READ(data_copies, j, loc) ^ current_bit);
LOCK_MEMORY_SEGMENT(j);
corrections++;
}
}

current_bit <<= 1;

}

return corrections;
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7 changes: 0 additions & 7 deletions msp430/environment.h
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Original file line number Diff line number Diff line change
@@ -1,13 +1,6 @@
#ifndef ENVIRONMENT_H
#define ENVIRONMENT_H

/*
* Environment Settings
*/

// Defines the size of the static agreements list
#define NUM_CODE_COPIES 3

/*
* MSP430 Microcontroller environment-specific code
*/
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