Adds 16-bit support for pnm files.

stb_image.h

@@ -108,7 +108,7 @@ RECENT REVISION HISTORY:
     Cass Everitt            Ryamond Barbiero                        github:grim210
     Paul Du Bois            Engin Manap        Aldo Culquicondor    github:sammyhw
     Philipp Wiesemann       Dale Weiler        Oriol Ferrer Mesia   github:phprus
-    Josh Tobin                                 Matthew Gregan       github:poppolopoppo
+    Josh Tobin              Simon Breuss       Matthew Gregan       github:poppolopoppo
     Julian Raschke          Gregory Mullen     Christian Floisand   github:darealshinji
     Baldur Karlsson         Kevin Schmidt      JR Smith             github:Michaelangel007
                             Brad Weinberger    Matvey Cherevko      [reserved]
@@ -935,6 +935,7 @@ static int      stbi__gif_info(stbi__context *s, int *x, int *y, int *comp);
 static int      stbi__pnm_test(stbi__context *s);
 static void    *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req_comp, stbi__result_info *ri);
 static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp);
+static int      stbi__pnm_is16(stbi__context *s);
 #endif
 
 static
@@ -7322,7 +7323,8 @@ static void *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req
    stbi_uc *out;
    STBI_NOTUSED(ri);
 
-   if (!stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y, (int *)&s->img_n))
+   ri->bits_per_channel = stbi__pnm_info(s, (int *)&s->img_x, (int *)&s->img_y, (int *)&s->img_n);
+   if (ri->bits_per_channel == 0)
       return 0;
 
    if (s->img_y > STBI_MAX_DIMENSIONS) return stbi__errpuc("too large","Very large image (corrupt?)");
@@ -7332,12 +7334,12 @@ static void *stbi__pnm_load(stbi__context *s, int *x, int *y, int *comp, int req
    *y = s->img_y;
    if (comp) *comp = s->img_n;
 
-   if (!stbi__mad3sizes_valid(s->img_n, s->img_x, s->img_y, 0))
+   if (!stbi__mad4sizes_valid(s->img_n, s->img_x, s->img_y, ri->bits_per_channel / 8, 0))
       return stbi__errpuc("too large", "PNM too large");
 
-   out = (stbi_uc *) stbi__malloc_mad3(s->img_n, s->img_x, s->img_y, 0);
+   out = (stbi_uc *) stbi__malloc_mad4(s->img_n, s->img_x, s->img_y, ri->bits_per_channel / 8, 0);
    if (!out) return stbi__errpuc("outofmem", "Out of memory");
-   stbi__getn(s, out, s->img_n * s->img_x * s->img_y);
+   stbi__getn(s, out, s->img_n * s->img_x * s->img_y * (ri->bits_per_channel / 8));
 
    if (req_comp && req_comp != s->img_n) {
       out = stbi__convert_format(out, s->img_n, req_comp, s->img_x, s->img_y);
@@ -7413,12 +7415,21 @@ static int      stbi__pnm_info(stbi__context *s, int *x, int *y, int *comp)
    stbi__pnm_skip_whitespace(s, &c);
 
    maxv = stbi__pnm_getinteger(s, &c);  // read max value
-
-   if (maxv > 255)
-      return stbi__err("max value > 255", "PPM image not 8-bit");
+   if (maxv > 65535)
+      return stbi__err("max value > 65535", "PPM image supports only 8-bit and 16-bit images");
+   else if (maxv > 255)
+      return 16;
    else
-      return 1;
+      return 8;
 }
+
+static int stbi__pnm_is16(stbi__context *s)
+{
+   if (stbi__pnm_info(s, NULL, NULL, NULL) == 16)
+	   return 1;
+   return 0;
+}
+
 #endif
 
 static int stbi__info_main(stbi__context *s, int *x, int *y, int *comp)
@@ -7473,6 +7484,9 @@ static int stbi__is_16_main(stbi__context *s)
    if (stbi__psd_is16(s))  return 1;
    #endif
 
+   #ifndef STBI_NO_PNM
+   if (stbi__pnm_is16(s))  return 1;
+   #endif
    return 0;
 }