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Wording, whitespace

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This commit is contained in:
Dominic Szablewski 2021-12-08 15:32:43 +01:00
parent 92f7ebd3f8
commit 6a73cc65c5
1 changed files with 18 additions and 18 deletions
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36
qoi.h
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@ -95,22 +95,21 @@ The decoder and encoder start with {r: 0, g: 0, b: 0, a: 255} as the previous
pixel value. Pixels are either encoded as
- a run of the previous pixel
- an index into a previously seen pixel
- a difference to the previous pixel value in r,g,b,a
- full r,g,b,a values
- a difference to the previous pixel value in r,g,b
- full r,g,b or r,g,b,a values
A running array[64] of previously seen pixel values is maintained by the encoder
and decoder. Each pixel that is seen by the encoder and decoder is put into this
array at the position (r * 3 + g * 5 + b * 7) % 64. In the encoder, if the pixel
value at this index matches the current pixel, this index position is written to
the stream.
array at the position (r * 3 + g * 5 + b * 7 + a * 11) % 64. In the encoder, if
the pixel value at this index matches the current pixel, this index position is
written to the stream as QOI_OP_INDEX.
Each chunk starts with a 8 or 2 bit tag, followed by a number of data bits.
The bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned.
All values encoded in these data bits have the most significant bit (MSB) on the
left.
Each chunk starts with a 2 or 8 bit tag, followed by a number of data bits. The
bit length of chunks is divisible by 8 - i.e. all chunks are byte aligned. All
values encoded in these data bits have the most significant bit on the left.
The 8-bit tags have precedence over the 2-bit tags. A decoder must check the
8-bit tags first.
The 8-bit tags have precedence over the 2-bit tags. A decoder must check for the
presence of an 8-bit tag first.
The possible chunks are:
@ -216,15 +215,16 @@ within the stream.
extern "C" {
#endif
// A pointer to qoi_desc struct has to be supplied to all of qoi's functions. It
// describes either the input format (for qoi_write, qoi_encode), or is filled
// with the description read from the file header (for qoi_read, qoi_decode).
// A pointer to a qoi_desc struct has to be supplied to all of qoi's functions.
// It describes either the input format (for qoi_write and qoi_encode), or is
// filled with the description read from the file header (for qoi_read and
// qoi_decode).
// The colorspace in this qoi_desc is an enum where
// 0 = sRGB, i.e. gamma scaled RGB channels and a linear alpha channel
// 1 = all channels are linear
// You may use the the constants QOI_SRGB or QOI_LINEAR. The colorspace is
// purely informative. It will be saved to the file header, but does not affect
// You may use the constants QOI_SRGB or QOI_LINEAR. The colorspace is purely
// informative. It will be saved to the file header, but does not affect
// en-/decoding in any way.
#define QOI_SRGB 0
@ -312,7 +312,7 @@ void *qoi_decode(const void *data, int size, qoi_desc *desc, int channels);
#define QOI_MASK_2 0xc0 // 11000000
#define QOI_COLOR_HASH(C) (C.rgba.r * 3 + C.rgba.g * 5 + C.rgba.b * 7 + C.rgba.a * 11)
#define QOI_COLOR_HASH(C) (C.rgba.r*3 + C.rgba.g*5 + C.rgba.b*7 + C.rgba.a*11)
#define QOI_MAGIC \
(((unsigned int)'q') << 24 | ((unsigned int)'o') << 16 | \
((unsigned int)'i') << 8 | ((unsigned int)'f'))
@ -422,7 +422,7 @@ void *qoi_encode(const void *data, const qoi_desc *desc, int *out_len) {
vg > -3 && vg < 2 &&
vb > -3 && vb < 2
) {
bytes[p++] = QOI_OP_DIFF | ((vr + 2) << 4) | (vg + 2) << 2 | (vb + 2);
bytes[p++] = QOI_OP_DIFF | (vr + 2) << 4 | (vg + 2) << 2 | (vb + 2);
}
else if (
vg_r > -9 && vg_r < 8 &&