public static void *stbi__load_main(stbi__context s, int *x, int *y, int *comp, int req_comp,
stbi__result_info *ri, int bpc)
{
CRuntime.memset(ri, 0, (ulong)sizeof(stbi__result_info));
ri->bits_per_channel = 8;
ri->channel_order = STBI_ORDER_RGB;
ri->num_channels = 0;
if (stbi__png_test(s) != 0)
{
return(stbi__png_load(s, x, y, comp, req_comp, ri));
}
if (stbi__bmp_test(s) != 0)
{
return(stbi__bmp_load(s, x, y, comp, req_comp, ri));
}
if (stbi__gif_test(s) != 0)
{
return(stbi__gif_load(s, x, y, comp, req_comp, ri));
}
if (stbi__psd_test(s) != 0)
{
return(stbi__psd_load(s, x, y, comp, req_comp, ri, bpc));
}
if (stbi__jpeg_test(s) != 0)
{
return(stbi__jpeg_load(s, x, y, comp, req_comp, ri));
}
if (stbi__hdr_test(s) != 0)
{
var hdr = stbi__hdr_load(s, x, y, comp, req_comp, ri);
return(stbi__hdr_to_ldr(hdr, *x, *y, req_comp != 0 ? req_comp : *comp));
}
if (stbi__tga_test(s) != 0)
{
return(stbi__tga_load(s, x, y, comp, req_comp, ri));
}
return((byte *)(ulong)(stbi__err("unknown image type") != 0 ? 0 : 0));
}
public static byte *stbi__gif_load_next(stbi__context s, stbi__gif g, int *comp, int req_comp, byte *two_back)
{
var dispose = 0;
var first_frame = 0;
var pi = 0;
var pcount = 0;
first_frame = 0;
if (g._out_ == null)
{
if (stbi__gif_header(s, g, comp, 0) == 0)
{
return(null);
}
if (stbi__mad3sizes_valid(4, g.w, g.h, 0) == 0)
{
return((byte *)(ulong)(stbi__err("too large") != 0 ? 0 : 0));
}
pcount = g.w * g.h;
g._out_ = (byte *)stbi__malloc((ulong)(4 * pcount));
g.background = (byte *)stbi__malloc((ulong)(4 * pcount));
g.history = (byte *)stbi__malloc((ulong)pcount);
if (g._out_ == null || g.background == null || g.history == null)
{
return((byte *)(ulong)(stbi__err("outofmem") != 0 ? 0 : 0));
}
CRuntime.memset(g._out_, 0x00, (ulong)(4 * pcount));
CRuntime.memset(g.background, 0x00, (ulong)(4 * pcount));
CRuntime.memset(g.history, 0x00, (ulong)pcount);
first_frame = 1;
}
else
{
dispose = (g.eflags & 0x1C) >> 2;
pcount = g.w * g.h;
if (dispose == 3 && two_back == null)
{
dispose = 2;
}
if (dispose == 3)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.history[pi] != 0)
{
CRuntime.memcpy(&g._out_[pi * 4], &two_back[pi * 4], (ulong)4);
}
}
}
else if (dispose == 2)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.history[pi] != 0)
{
CRuntime.memcpy(&g._out_[pi * 4], &g.background[pi * 4], (ulong)4);
}
}
}
CRuntime.memcpy(g.background, g._out_, (ulong)(4 * g.w * g.h));
}
CRuntime.memset(g.history, 0x00, (ulong)(g.w * g.h));
for (; ;)
{
int tag = stbi__get8(s);
switch (tag)
{
case 0x2C:
{
var x = 0;
var y = 0;
var w = 0;
var h = 0;
byte *o;
x = stbi__get16le(s);
y = stbi__get16le(s);
w = stbi__get16le(s);
h = stbi__get16le(s);
if (x + w > g.w || y + h > g.h)
{
return((byte *)(ulong)(stbi__err("bad Image Descriptor") != 0 ? 0 : 0));
}
g.line_size = g.w * 4;
g.start_x = x * 4;
g.start_y = y * g.line_size;
g.max_x = g.start_x + w * 4;
g.max_y = g.start_y + h * g.line_size;
g.cur_x = g.start_x;
g.cur_y = g.start_y;
if (w == 0)
{
g.cur_y = g.max_y;
}
g.lflags = stbi__get8(s);
if ((g.lflags & 0x40) != 0)
{
g.step = 8 * g.line_size;
g.parse = 3;
}
else
{
g.step = g.line_size;
g.parse = 0;
}
if ((g.lflags & 0x80) != 0)
{
stbi__gif_parse_colortable(s, g.lpal, 2 << (g.lflags & 7),
(g.eflags & 0x01) != 0 ? g.transparent : -1);
g.color_table = (byte *)g.lpal;
}
else if ((g.flags & 0x80) != 0)
{
g.color_table = (byte *)g.pal;
}
else
{
return((byte *)(ulong)(stbi__err("missing color table") != 0 ? 0 : 0));
}
o = stbi__process_gif_raster(s, g);
if (o == null)
{
return(null);
}
pcount = g.w * g.h;
if (first_frame != 0 && g.bgindex > 0)
{
for (pi = 0; pi < pcount; ++pi)
{
if (g.history[pi] == 0)
{
g.pal[g.bgindex][3] = 255;
CRuntime.memcpy(&g._out_[pi * 4], &g.pal[g.bgindex], (ulong)4);
}
}
}
return(o);
}
case 0x21:
{
var len = 0;
int ext = stbi__get8(s);
if (ext == 0xF9)
{
len = stbi__get8(s);
if (len == 4)
{
g.eflags = stbi__get8(s);
g.delay = 10 * stbi__get16le(s);
if (g.transparent >= 0)
{
g.pal[g.transparent][3] = 255;
}
if ((g.eflags & 0x01) != 0)
{
g.transparent = stbi__get8(s);
if (g.transparent >= 0)
{
g.pal[g.transparent][3] = 0;
}
}
else
{
stbi__skip(s, 1);
g.transparent = -1;
}
}
else
{
stbi__skip(s, len);
break;
}
}
while ((len = stbi__get8(s)) != 0)
{
stbi__skip(s, len);
}
break;
}
case 0x3B:
return(null);
default:
return((byte *)(ulong)(stbi__err("unknown code") != 0 ? 0 : 0));
}
}
}
public static int stbi__zbuild_huffman(stbi__zhuffman *z, byte *sizelist, int num)
{
var i = 0;
var k = 0;
var code = 0;
var next_code = stackalloc int[16];
var sizes = stackalloc int[17];
CRuntime.memset(sizes, 0, (ulong)sizeof(int));
CRuntime.memset(z->fast, 0, (ulong)((1 << 9) * sizeof(ushort)));
for (i = 0; i < num; ++i)
{
++sizes[sizelist[i]];
}
sizes[0] = 0;
for (i = 1; i < 16; ++i)
{
if (sizes[i] > 1 << i)
{
return(stbi__err("bad sizes"));
}
}
code = 0;
for (i = 1; i < 16; ++i)
{
next_code[i] = code;
z->firstcode[i] = (ushort)code;
z->firstsymbol[i] = (ushort)k;
code = code + sizes[i];
if (sizes[i] != 0)
{
if (code - 1 >= 1 << i)
{
return(stbi__err("bad codelengths"));
}
}
z->maxcode[i] = code << (16 - i);
code <<= 1;
k += sizes[i];
}
z->maxcode[16] = 0x10000;
for (i = 0; i < num; ++i)
{
var s = (int)sizelist[i];
if (s != 0)
{
var c = next_code[s] - z->firstcode[s] + z->firstsymbol[s];
var fastv = (ushort)((s << 9) | i);
z->size[c] = (byte)s;
z->value[c] = (ushort)i;
if (s <= 9)
{
var j = stbi__bit_reverse(next_code[s], s);
while (j < 1 << 9)
{
z->fast[j] = fastv;
j += 1 << s;
}
}
++next_code[s];
}
}
return(1);
}
public static int stbi__compute_huffman_codes(stbi__zbuf *a)
{
var z_codelength = new stbi__zhuffman();
var lencodes = stackalloc byte[286 + 32 + 137];
var codelength_sizes = stackalloc byte[19];
var i = 0;
var n = 0;
var hlit = (int)(stbi__zreceive(a, 5) + 257);
var hdist = (int)(stbi__zreceive(a, 5) + 1);
var hclen = (int)(stbi__zreceive(a, 4) + 4);
var ntot = hlit + hdist;
CRuntime.memset(codelength_sizes, 0, (ulong)(19 * sizeof(byte)));
for (i = 0; i < hclen; ++i)
{
var s = (int)stbi__zreceive(a, 3);
codelength_sizes[length_dezigzag[i]] = (byte)s;
}
if (stbi__zbuild_huffman(&z_codelength, codelength_sizes, 19) == 0)
{
return(0);
}
n = 0;
while (n < ntot)
{
var c = stbi__zhuffman_decode(a, &z_codelength);
if (c < 0 || c >= 19)
{
return(stbi__err("bad codelengths"));
}
if (c < 16)
{
lencodes[n++] = (byte)c;
}
else
{
var fill = (byte)0;
if (c == 16)
{
c = (int)(stbi__zreceive(a, 2) + 3);
if (n == 0)
{
return(stbi__err("bad codelengths"));
}
fill = lencodes[n - 1];
}
else if (c == 17)
{
c = (int)(stbi__zreceive(a, 3) + 3);
}
else
{
c = (int)(stbi__zreceive(a, 7) + 11);
}
if (ntot - n < c)
{
return(stbi__err("bad codelengths"));
}
CRuntime.memset(lencodes + n, fill, (ulong)c);
n += c;
}
}
if (n != ntot)
{
return(stbi__err("bad codelengths"));
}
if (stbi__zbuild_huffman(&a->z_length, lencodes, hlit) == 0)
{
return(0);
}
if (stbi__zbuild_huffman(&a->z_distance, lencodes + hlit, hdist) == 0)
{
return(0);
}
return(1);
}