Changeset 36024 for grass/branches/develbranch_6/lib/gis/null_val.c

Timestamp:

Feb 22, 2009, 12:54:28 AM (15 years ago)

Author:

hamish

Message:

backport faster null check for G_is_c_null_value() (trac #392)

File:

• grass/branches/develbranch_6/lib/gis/null_val.c (modified) (6 diffs)

grass/branches/develbranch_6/lib/gis/null_val.c

@@ -25 +25 @@
 #include <grass/glocale.h>
 
-/*======================= Internal Constants/Defines =======================*/
-
-/* none */
-
-/*========================== Internal Typedefs =============================*/
-
-/* none */
-
-/*====================== Static Variable Declaration =======================*/
-
-/* Null pattern variables */
-static CELL cellNullPattern;
-static FCELL fcellNullPattern;
-static DCELL dcellNullPattern;
-
-/* Flag to indicate null patterns are initialized */
-static int initialized = FALSE;
-
-/*============================== Prototypes ================================*/
-
 static int EmbedGivenNulls(void *, char *, RASTER_MAP_TYPE, int);
-static void InitError(void);
-
-/*======================= Internal Static Functions ========================*/
 
 /****************************************************************************
@@ -97 +74 @@
 }
 
-/****************************************************************************
-* void InitError (void)
-*
-* PURPOSE:      To print an error message and exit the program. This function
-*               is called if something tries to access a null pattern before
-*               it is initialized.
-* INPUT VARS:   none
-* RETURN VAL:   none
-*****************************************************************************/
-static void InitError(void)
-{
-    char errMsg[512];           /* array to hold error message */
-
-    strcpy(errMsg, _("Null values have not been initialized. "));
-    strcat(errMsg, _("G_gisinit() must be called first. "));
-    strcat(errMsg, _("Please advise GRASS developers of this error.\n"));
-    G_fatal_error(errMsg);
-
-    return;
-}
-
 /*========================== Library Functions =============================*/
-
-/****************************************************************************
-* void G__init_null_patterns (void)
-*
-* PURPOSE:      To initialize the three null patterns for CELL, FCELL, and
-*               DCELL data types. It also sets the initialized flag to TRUE.
-*               This function is called by G_gisinit()
-* INPUT VARS:   none
-* RETURN VAL:   none
-*****************************************************************************/
-void G__init_null_patterns(void)
-{
-    unsigned char *bytePtr;     /* pointer to traverse FCELL and DCELL */
-    int numBits;                /* number of bits for CELL type */
-    int i;                      /* counter */
-
-    if (!initialized) {
-        /* Create the null pattern for the CELL data type - set the left */
-        /* most bit to 1 and the rest to 0, basically INT_MIN. Since CELL is */
-        /* some type of integer the bytes are not split into exponent and */
-        /* mantissa. Thus a simple left shift can be used */
-        numBits = sizeof(CELL) * 8;
-
-        cellNullPattern = 1 << (numBits - 1);
-
-        /* Create the null pattern for the FCELL data type - set all bits */
-        /* to 1, basically NaN. Need to use a byte pointer since bytes */
-        /* represent the exponent and mantissa */
-        bytePtr = (unsigned char *)&fcellNullPattern;
-
-        for (i = 0; i < sizeof(FCELL); i++) {
-            *bytePtr = (unsigned char)255;
-            bytePtr++;
-        }
-
-        /* Create the null pattern for the DCELL data type - set all bits */
-        /* to 1, basically NaN. Need to use a byte pointer since bytes */
-        /* represent the exponent and mantissa */
-        bytePtr = (unsigned char *)&dcellNullPattern;
-
-        for (i = 0; i < sizeof(DCELL); i++) {
-            *bytePtr = (unsigned char)255;
-            bytePtr++;
-        }
-
-        /* Set the initialized flag to TRUE */
-        initialized = TRUE;
-    }
-
-    return;
-}
 
 /****************************************************************************
@@ -235 +140 @@
 * RETURN VAL:   none
 *****************************************************************************/
-void G_set_c_null_value(CELL * cellVals, int numVals)
-{
-    CELL *cellPtr;              /* pointer to CELL array to set to null */
+void G_set_c_null_value(CELL *cellVals, int numVals)
+{
     int i;                      /* counter */
 
-    /* Check if the null patterns have been initialized */
-    if (!initialized) {
-        InitError();
-    }
-
-    /* Set numVals consecutive CELL values to null */
-    cellPtr = cellVals;
-
-    for (i = 0; i < numVals; i++) {
-        *cellPtr = cellNullPattern;
-        cellPtr++;
-    }
-
-    return;
+    for (i = 0; i < numVals; i++)
+        cellVals[i] = (int) 0x80000000;
 }
 
@@ -264 +156 @@
 * RETURN VAL:   none
 *****************************************************************************/
-void G_set_f_null_value(FCELL * fcellVals, int numVals)
-{
-    FCELL *fcellPtr;            /* pointer to FCELL array to set to null */
-    int i;                      /* counter */
-
-    /* Check if the null patterns have been initialized */
-    if (!initialized) {
-        InitError();
-    }
-
-    /* Set numVals consecutive FCELL values to null */
-    fcellPtr = fcellVals;
-
-    for (i = 0; i < numVals; i++) {
-        *fcellPtr = fcellNullPattern;
-        fcellPtr++;
-    }
-
-    return;
+void G_set_f_null_value(FCELL *fcellVals, int numVals)
+{
+    static const unsigned char null_bits[4] = {
+        0xFF, 0xFF, 0xFF, 0xFF};
+    int i;
+
+    for (i = 0; i < numVals; i++)
+        memcpy(&fcellVals[i], null_bits, sizeof(null_bits));
 }
 
@@ -293 +174 @@
 * RETURN VAL:   none
 *****************************************************************************/
-void G_set_d_null_value(DCELL * dcellVals, int numVals)
-{
-    DCELL *dcellPtr;            /* pointer to DCELL array to set to null */
-    int i;                      /* counter */
-
-    /* Check if the null patterns have been initialized */
-    if (!initialized) {
-        InitError();
-    }
-
-    /* Set numVals consecutive DCELL values to null */
-    dcellPtr = dcellVals;
-
-    for (i = 0; i < numVals; i++) {
-        *dcellPtr = dcellNullPattern;
-        dcellPtr++;
-    }
-
-    return;
+void G_set_d_null_value(DCELL *dcellVals, int numVals)
+{
+    static const unsigned char null_bits[8] = {
+        0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
+    int i;
+
+    for (i = 0; i < numVals; i++)
+        memcpy(&dcellVals[i], null_bits, sizeof(null_bits));
 }
 
@@ -374 +244 @@
 int G_is_c_null_value(const CELL * cellVal)
 {
-    int i;                      /* counter */
-
-    /* Check if the null patterns have been initialized */
-    if (!initialized) {
-        InitError();
-    }
-
     /* Check if the CELL value matches the null pattern */
-    for (i = 0; i < sizeof(CELL); i++) {
-        if (((unsigned char *)cellVal)[i] !=
-            ((unsigned char *)&cellNullPattern)[i]) {
-            return FALSE;
-        }
-    }
-
-    return TRUE;
+    return *cellVal == (CELL) 0x80000000;
 }