On Thu, May 16, 2019 at 09:35:00PM +1000, Peter Ross wrote:
> +static int read_mb_value(GetBitContext *gb)
> +{
> + int v = 1;
> + int size;
> + OPEN_READER(re, gb);
> +
> + do {
> + int bit;
> + size = 0;
> +
> + UPDATE_CACHE(re, gb);
> + bit = SHOW_UBITS(re, gb, 1);
> + SKIP_BITS(re, gb, 1);
> + if (!bit)
> + break;
> +
> + do {
> + bit = SHOW_UBITS(re, gb, 1);
> + SKIP_BITS(re, gb, 1);
> + if (!bit)
> + break;
> + size++;
> + } while (size < 8);
> +
> + v += 1 << size;
> +
> + } while (size == 8);
> +
> + if (size) {
> + v += SHOW_UBITS(re, gb, size);
> + LAST_SKIP_BITS(re, gb, size);
> + }
> +
> + CLOSE_READER(re, gb);
> + return v;
> +}
I meant that you should do something like
(could maybe be made less messy, and not
sure it's really necessary to use the macro
version, I think it'd prefer the plain
show_bits etc)
int v = 0;
int bits = SHOW_UBITS(re, gb, 9);
while (bits == 0x1ff) {
// Note: relies on 0-padding to guarantee termination!
SKIP_BITS(re, gb, 9);
bits = SHOW_UBITS(re, gb, 9);
}
if (bits < 0x100) {
LAST_SKIP_BITS(re, gb, 1);
v = 1;
} else if (bits < 0x180) {
LAST_SKIP_BITS(re, gb, 2);
v = 2;
} else if (bits < 0x1c0) {
LAST_SKIP_BITS(re, gb, 3 + 1);
v = 3 + ((bits >> 5) & 1);
} else if (bits < 0x1e0) {
LAST_SKIP_BITS(re, gb, 4 + 2);
v = 5 + ((bits >> 3) & 3);
} else if (bits < 0x1f0) {
LAST_SKIP_BITS(re, gb, 5 + 3);
v = 9 + ((bits >> 1) & 7);
} else if (bits < 0x1f8) {
SKIP_BITS(re, gb, 6);
v = 17 + SHOW_UBITS(re, gb, 4);
LAST_SKIP_BITS(re, gb, 4);
} else if (bits < 0x1fc) {
SKIP_BITS(re, gb, 7);
v = 33 + SHOW_UBITS(re, gb, 5);
LAST_SKIP_BITS(re, gb, 5);
} else if (bits < 0x1fe) {
SKIP_BITS(re, gb, 8);
v = 65 + SHOW_UBITS(re, gb, 6);
LAST_SKIP_BITS(re, gb, 6);
} else {
SKIP_BITS(re, gb, 9);
v = 127 + SHOW_UBITS(re, gb, 7);
LAST_SKIP_BITS(re, gb, 7);
}
CLOSE_READER(re, gb);
return v;
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