commit fb11e6913f9da9ae350befa6deb560c10ac0afcd

Author: Allison Vacanti <allison.vacanti@kitware.com>

Date:   Thu Oct 4 13:12:01 2018 -0400

    Improve small number writing in HPDF_FToA.

    This was truncating all numbers at 1e-5, now it ensures that 5

    significant figures will always be written for values > 1e-20.

diff --git a/include/hpdf_consts.h b/include/hpdf_consts.h

index 2dbf396..d874f7f 100644

--- a/include/hpdf_consts.h

+++ b/include/hpdf_consts.h

@@ -32,7 +32,7 @@

 /* buffer size which is required when we convert to character string. */

 #define HPDF_TMP_BUF_SIZ            512

 #define HPDF_SHORT_BUF_SIZ          32

-#define HPDF_REAL_LEN               11

+#define HPDF_REAL_LEN               64

 #define HPDF_INT_LEN                11

 #define HPDF_TEXT_DEFAULT_LEN       256

 #define HPDF_UNICODE_HEADER_LEN     2

diff --git a/include/hpdf_types.h b/include/hpdf_types.h

index a35fe8f..ce5cbd7 100644

--- a/include/hpdf_types.h

+++ b/include/hpdf_types.h

@@ -45,6 +45,12 @@ typedef  signed int          HPDF_INT;

 typedef  unsigned int        HPDF_UINT;

+/*  64bit integer types

+ */

+typedef  signed long long    HPDF_INT64;

+typedef  unsigned long long  HPDF_UINT64;

+

+

 /*  32bit integer types

  */

 typedef  signed int          HPDF_INT32;

diff --git a/src/hpdf_utils.c b/src/hpdf_utils.c

index 728da5a..6e9a8b7 100644

--- a/src/hpdf_utils.c

+++ b/src/hpdf_utils.c

@@ -15,6 +15,7 @@

  *

  */

+#include <math.h>

 #include <stdlib.h>

 #include "hpdf_utils.h"

 #include "hpdf_consts.h"

@@ -188,6 +189,10 @@ HPDF_FToA  (char       *s,

     char* sptr = s;

     char* t;

     HPDF_UINT32 i;

+    HPDF_UINT32 prec;

+    HPDF_INT32 logVal;

+    HPDF_REAL roundInc;

+    HPDF_INT64 fShift;

     if (val > HPDF_LIMIT_MAX_REAL)

         val = HPDF_LIMIT_MAX_REAL;

@@ -203,12 +208,24 @@ HPDF_FToA  (char       *s,

         val = -val;

     }

+    /* Compute the decimal precision to write at least 5 significant figures */

+    logVal = (HPDF_INT32)(val > 1e-20 ? log10(val) : 0.);

+    if (logVal >= 0) {

+        prec = 5;

+    }

+    else {

+        prec = -logVal + 5;

+    }

+

+    roundInc = 0.5 * (1. / pow((HPDF_REAL)10, (HPDF_REAL)prec));

+    fShift = (HPDF_INT64)pow((HPDF_REAL)10, (HPDF_REAL)prec);

+

     /* separate an integer part and a decimal part. */

-    int_val = (HPDF_INT32)(val + 0.000005);

-    fpart_val = (HPDF_INT32)((HPDF_REAL)(val - int_val + 0.000005) * 100000);

+    int_val = (HPDF_INT64)(val + roundInc);

+    fpart_val = (HPDF_INT64)((HPDF_REAL)(val - int_val + roundInc) * fShift);

     /* process decimal part */

-    for (i = 0; i < 5; i++) {

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

         *t = (char)((char)(fpart_val % 10) + '0');

         fpart_val /= 10;

         t--;