stb_sprintf: fix unaligned digitpair[], fix some signed-right-shifts

stb_sprintf.h

@@ -16,6 +16,7 @@
 //    Marcin Wojdyr
 //    Leonard Ritter
 //    Stefano Zanotti
+//    Adam Allison
 //
 // LICENSE:
 //
@@ -226,11 +227,18 @@ static stbsp__int32 stbsp__real_to_parts(stbsp__int64 *bits, stbsp__int32 *expo,
 
 static char stbsp__period = '.';
 static char stbsp__comma = ',';
-static char stbsp__digitpair[201] =
+static struct
+{
+   short temp; // force next field to be 2-byte aligned
+   char pair[201];
+} stbsp__digitpair =
+{
+  0,
    "00010203040506070809101112131415161718192021222324"
    "25262728293031323334353637383940414243444546474849"
    "50515253545556575859606162636465666768697071727374"
-   "75767778798081828384858687888990919293949596979899";
+   "75767778798081828384858687888990919293949596979899"
+};
 
 STBSP__PUBLICDEF void STB_SPRINTF_DECORATE(set_separators)(char pcomma, char pperiod)
 {
@@ -687,7 +695,7 @@ STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback,
          if (dp > 0) {
             pr = (dp < (stbsp__int32)l) ? l - dp : 0;
          } else {
-            pr = -dp + ((pr > (stbsp__int32)l) ? l : pr);
+            pr = -dp + ((pr > (stbsp__int32)l) ? (stbsp__int32) l : pr);
          }
          goto dofloatfromg;
 
@@ -1047,7 +1055,7 @@ STBSP__PUBLICDEF int STB_SPRINTF_DECORATE(vsprintfcb)(STBSP_SPRINTFCB *callback,
             if ((fl & STBSP__TRIPLET_COMMA) == 0) {
                do {
                   s -= 2;
-                  *(stbsp__uint16 *)s = *(stbsp__uint16 *)&stbsp__digitpair[(n % 100) * 2];
+                  *(stbsp__uint16 *)s = *(stbsp__uint16 *)&stbsp__digitpair.pair[(n % 100) * 2];
                   n /= 100;
                } while (n);
             }
@@ -1445,7 +1453,7 @@ static stbsp__int32 stbsp__real_to_parts(stbsp__int64 *bits, stbsp__int32 *expo,
    *bits = b & ((((stbsp__uint64)1) << 52) - 1);
    *expo = (stbsp__int32)(((b >> 52) & 2047) - 1023);
 
-   return (stbsp__int32)(b >> 63);
+   return (stbsp__int32)((stbsp__uint64) b >> 63);
 }
 
 static double const stbsp__bot[23] = {
@@ -1655,7 +1663,7 @@ static stbsp__int32 stbsp__real_to_str(char const **start, stbsp__uint32 *len, c
    d = value;
    STBSP__COPYFP(bits, d);
    expo = (stbsp__int32)((bits >> 52) & 2047);
-   ng = (stbsp__int32)(bits >> 63);
+   ng = (stbsp__int32)((stbsp__int64) bits >> 63);
    if (ng)
       d = -d;
 
@@ -1765,7 +1773,7 @@ static stbsp__int32 stbsp__real_to_str(char const **start, stbsp__uint32 *len, c
       }
       while (n) {
          out -= 2;
-         *(stbsp__uint16 *)out = *(stbsp__uint16 *)&stbsp__digitpair[(n % 100) * 2];
+         *(stbsp__uint16 *)out = *(stbsp__uint16 *)&stbsp__digitpair.pair[(n % 100) * 2];
          n /= 100;
          e += 2;
       }