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Improve HCA key detection in rare cases [Ryu ga Gotoku Online (Mobile)]

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This commit is contained in:
bnnm 2019-07-07 15:26:15 +02:00
parent 6f2c94b303
commit b9d01e3176
1 changed files with 16 additions and 4 deletions
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20
ext_libs/clHCA.c
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@ -925,10 +925,11 @@ void clHCA_SetKey(clHCA *hca, unsigned long long keycode) {
}
int clHCA_TestBlock(clHCA *hca, void *data, unsigned int size) {
const int frame_samples = HCA_SUBFRAMES_PER_FRAME * HCA_SAMPLES_PER_SUBFRAME;
const float scale = 32768.0f;
unsigned int ch, sf, s;
int status;
int clips = 0, blanks = 0;
int clips = 0, blanks = 0, channel_blanks[HCA_MAX_CHANNELS] = {0};
/* first blocks can be empty/silent, check all bytes but sync/crc */
@ -965,8 +966,10 @@ int clHCA_TestBlock(clHCA *hca, void *data, unsigned int size) {
}
else {
signed int psample = (signed int) (fsample * scale);
if (psample == 0 || psample == -1)
if (psample == 0 || psample == -1) {
blanks++;
channel_blanks[ch]++;
}
}
}
}
@ -974,13 +977,22 @@ int clHCA_TestBlock(clHCA *hca, void *data, unsigned int size) {
/* the more clips the less likely block was correctly decrypted */
if (clips == 1)
clips++;
clips++; /* signal not full score */
if (clips > 1)
return clips;
/* if block is silent result is not useful */
if (blanks == hca->channels * HCA_SUBFRAMES_PER_FRAME * HCA_SAMPLES_PER_SUBFRAME)
if (blanks == hca->channels * frame_samples)
return 0;
/* some bad keys make left channel null and right normal enough (due to joint stereo stuff);
* it's possible real keys could do this but don't give full marks just in case */
if (hca->channels >= 2) {
/* only check main L/R, other channels like BL/BR are probably not useful */
if (channel_blanks[0] == frame_samples && channel_blanks[1] != frame_samples) /* maybe should check max/min values? */
return 3;
}
/* block may be correct (but wrong keys can get this too and should test more blocks) */
return 1;
}