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#include <xc.h>
#include <stdint.h>
#include "types.h"
#include "eeprom.h"
#include "table.h"
Status
tabWrite(const Table *tab, U8 k, U16 key, U16 val) {
if (k >= TAB_ROWS) {
return FAIL;
}
U16 addr = addU16U8(tab->offset, k*TAB_ROW_SIZE);
U8 row[4u] = {key.lo, key.hi, val.lo, val.hi};
return eepromWrite(addr, row, sizeof(row));
}
Status
tabRead(const Table *tab, U8 k, U16 *key, U16 *val) {
U16 addr;
U8 row[4u];
Status status;
if (k >= TAB_ROWS) {
return FAIL;
}
addr = addU16U8(tab->offset, k*TAB_ROW_SIZE);
status = eepromRead(addr, row, sizeof(row));
*key = (U16){.lo=row[0u], .hi=row[1u]};
*val = (U16){.lo=row[2u], .hi=row[3u]};
return status;
}
Status
tabLookup(const Table *tab, U16 key, U16 *val) {
U8 k;
U16 tkey, tval1, tval2;
Status status;
I8 ord;
// Search for key
for (k = 0u; (k < TAB_ROWS-1u); k++) {
status = tabRead(tab, k, &tkey, &tval1);
if (status != OK) {
return FAIL;
}
ord = cmpU16(key, tkey);
if (ord == 0u) { // found exact key
*val = tval1;
return OK;
} else if (ord > 0u) { // interpolate
status = tabRead(tab, k+1u, &tkey, &tval2);
if (status != OK) {
return FAIL;
}
// Mean: (tval1+tval2)/2
*val = rshiftU16(addU16(tval1, tval2), 1u);
return OK;
} else { // less
// continue
}
}
// Reached last row
*val = tval1; // last value in table
return OK;
}
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