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refactor: nibble-pack relstatus arrays to halve their memory footprint #125

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Merged
antLI-dev merged 1 commit into from
Jun 23, 2026
Merged

refactor: nibble-pack relstatus arrays to halve their memory footprint #125

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55 changes: 36 additions & 19 deletions src/snapspec/dbl4_adc_sdc.c
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@
#include "network/network.h"
#include "nanoflann/nanoflann.hpp"

/* relstatus array entries are nibble-packed (two per byte); values must not exceed 15. */
#define SDC_STS_UNKNOWN 1 /* Mark to be assigned at current order */
#define SDC_STS_FAIL 2 /* Mark has failed at current order */
#define SDC_STS_PASS 3 /* Mark has passed at current order */
Expand Down Expand Up @@ -306,6 +307,24 @@ static void sdcWriteCompactLog( hSDCTestImp sdci, long stn1, long stn2,
static long sdcStationId( hSDCTestImp sdci, int istn );
static void sdcTimeStamp( hSDCTestImp sdci, const char *status );

/* nibble_get/nibble_set: pack two SDC_STS_* values per byte in the relstatus row
* arrays, halving their memory footprint. data is the row's packed byte array.
* k is the column offset within the row (col - col0). An even-valued k occupies
* the lower nibble of byte k/2, odd-valued k the upper nibble. */
static inline void nibble_set(unsigned char *data, int k, unsigned char val)
{
/* 0 for even k (lower nibble), 4 for odd k (upper nibble). */
int shift = (k & 1) << 2;
/* Clear nibble, OR in val. */
data[k >> 1] = (data[k >> 1] & ~(0x0Fu << shift)) | ((unsigned char)val << shift);
}

static inline unsigned char nibble_get(const unsigned char *data, int k)
{
/* Shift target nibble to bits 3-0, mask off the rest. */
return (data[k >> 1] >> ((k & 1) << 2)) & 0x0F;
}

/*************************************************************************
** Function name: sdcCreateSDCTest
**//**
Expand Down Expand Up @@ -850,7 +869,7 @@ static unsigned char *sdcRAAllocRow( hSDCTestImp sdci, int row, int col0 )
hRABlock newalloc;

if( sdci->relstatus[row] ) return 0;
nalloc=row-col0+1;
nalloc=(row-col0+2)/2;

alloc=sdci->curalloc;
while( 1 )
Expand All @@ -874,6 +893,8 @@ static unsigned char *sdcRAAllocRow( hSDCTestImp sdci, int row, int col0 )
sdci->curalloc=alloc;
rowstatus=alloc->data+alloc->alloc;
alloc->alloc += nalloc;
/* Nibble-pack two SDC_STS_SKIP values into every element of rowstatus. */
memset(rowstatus, (SDC_STS_SKIP | (SDC_STS_SKIP << 4)), nalloc);
sdci->relstatus[row]=rowstatus;
sdci->relcol0[row]=col0;
return rowstatus;
Expand Down Expand Up @@ -1775,14 +1796,14 @@ static void sdcSetRelTestStatus( hSDCTestImp sdci, int istn, char status)

if( i <= nrelrow )
{
stsij=relstatus[i-col0];
stsij=nibble_get(relstatus,i-col0);
}
else
{
relstatus=sdci->relstatus[i];
col0=sdci->relcol0[i];
if( ! relstatus || col0 > nrelrow ) continue;
stsij=relstatus[nrelrow-col0];
stsij=nibble_get(relstatus,nrelrow-col0);
}

/*>> If the station has passed then .. */
Expand Down Expand Up @@ -2210,8 +2231,6 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
{
relstatus_col0 = jcands[0].j;
relstatus = sdcRAAllocRow(sdci, i, relstatus_col0);
if( relstatus )
memset(relstatus, SDC_STS_SKIP, i - relstatus_col0 + 1);
}
}

Expand All @@ -2226,11 +2245,6 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
else
{
j = jidx;
if( relstatus )
{
relstatus++;
*relstatus = SDC_STS_SKIP;
}
}

int istnj = sdci->lookup[j];
Expand Down Expand Up @@ -2271,15 +2285,17 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
{
if( kdtree_j )
{
/* Offset into pre-allocated relstatus row */
if( relstatus )
relstatus[j - relstatus_col0] = stsij;
nibble_set( relstatus, j - relstatus_col0, stsij );
}
else
{
if( ! relstatus )
relstatus=sdcRAAllocRow( sdci, i, j );
*relstatus = stsij;
{
relstatus = sdcRAAllocRow( sdci, i, j );
relstatus_col0 = j;
}
nibble_set( relstatus, j - relstatus_col0, stsij );
}
}
}
Expand Down Expand Up @@ -2318,7 +2334,7 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
if( ! relstatus ) continue;
if( ! passi && stsi != SDC_STS_UNKNOWN) continue;

for( j = col0; j < i; j++, relstatus++ )
for( j = col0; j < i; j++ )
{
int istnj = sdci->lookup[j];
long sdcstnj=sdcStationId(sdci,istnj);
Expand All @@ -2334,7 +2350,7 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes

/* If not passed or potential to pass then not interested */
if( ! passj && stsj != SDC_STS_UNKNOWN) continue;
if( *relstatus != SDC_STS_NEED_CVR ) continue;
if( nibble_get(relstatus, j - col0) != SDC_STS_NEED_CVR ) continue;

/*>> If trial phase of two pass calculation then record missing covariance,
else abort relative accuracy test */
Expand Down Expand Up @@ -2396,7 +2412,7 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
if( ! relstatus ) continue;
if( ! passi && stsi != SDC_STS_UNKNOWN) continue;

for( j = col0; j < i; relstatus++, j++ )
for( j = col0; j < i; j++ )
{
int istnj = sdci->lookup[j];
hSDCStation stnj = &(stns[istnj]);
Expand All @@ -2408,7 +2424,8 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
sts = utlCheckAbort();
if( sts != STS_OK ) return sts;
}
if( *relstatus == SDC_STS_SKIP ) continue;
unsigned char stsij_rel = nibble_get(relstatus, j - col0);
if( stsij_rel == SDC_STS_SKIP ) continue;

if( ! passj && stsj != SDC_STS_UNKNOWN) continue;
if( passi && passj ) continue;
Expand All @@ -2417,7 +2434,7 @@ static StatusType sdcSetupRelAccuracyStatus( hSDCTestImp sdci, hSDCOrderTest tes
stni->nreltest++;
stnj->nreltest++;

if( *relstatus == SDC_STS_FAIL )
if( stsij_rel == SDC_STS_FAIL )
{
/*>> If it fails, then increment count of fails for nodes
and if one or other node is already passed, the count of fails
Expand Down
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