static int16_t g726_decode(G726Context* c, int I) { int dq, re_signal, pk0, fa1, i, tr, ylint, ylfrac, thr2, al, dq0; Float11 f; int I_sig= I >> (c->code_size - 1); dq = inverse_quant(c, I); /* Transition detect */ ylint = (c->yl >> 15); ylfrac = (c->yl >> 10) & 0x1f; thr2 = (ylint > 9) ? 0x1f << 10 : (0x20 + ylfrac) << ylint; tr= (c->td == 1 && dq > ((3*thr2)>>2)); if (I_sig) /* get the sign */ dq = -dq; re_signal = (int16_t)(c->se + dq); /* Update second order predictor coefficient A2 and A1 */ pk0 = (c->sez + dq) ? sgn(c->sez + dq) : 0; dq0 = dq ? sgn(dq) : 0; if (tr) { c->a[0] = 0; c->a[1] = 0; for (i=0; i<6; i++) c->b[i] = 0; } else { /* This is a bit crazy, but it really is +255 not +256 */ fa1 = av_clip_intp2((-c->a[0]*c->pk[0]*pk0)>>5, 8); c->a[1] += 128*pk0*c->pk[1] + fa1 - (c->a[1]>>7); c->a[1] = av_clip(c->a[1], -12288, 12288); c->a[0] += 64*3*pk0*c->pk[0] - (c->a[0] >> 8); c->a[0] = av_clip(c->a[0], -(15360 - c->a[1]), 15360 - c->a[1]); for (i=0; i<6; i++) c->b[i] += 128*dq0*sgn(-c->dq[i].sign) - (c->b[i]>>8); } /* Update Dq and Sr and Pk */ c->pk[1] = c->pk[0]; c->pk[0] = pk0 ? pk0 : 1; c->sr[1] = c->sr[0]; i2f(re_signal, &c->sr[0]); for (i=5; i>0; i--) c->dq[i] = c->dq[i-1]; i2f(dq, &c->dq[0]); c->dq[0].sign = I_sig; /* Isn't it crazy ?!?! */ c->td = c->a[1] < -11776; /* Update Ap */ c->dms += (c->tbls.F[I]<<4) + ((- c->dms) >> 5); c->dml += (c->tbls.F[I]<<4) + ((- c->dml) >> 7); if (tr) c->ap = 256; else { c->ap += (-c->ap) >> 4; if (c->y <= 1535 || c->td || abs((c->dms << 2) - c->dml) >= (c->dml >> 3)) c->ap += 0x20; } /* Update Yu and Yl */ c->yu = av_clip(c->y + c->tbls.W[I] + ((-c->y)>>5), 544, 5120); c->yl += c->yu + ((-c->yl)>>6); /* Next iteration for Y */ al = (c->ap >= 256) ? 1<<6 : c->ap >> 2; c->y = (c->yl + (c->yu - (c->yl>>6))*al) >> 6; /* Next iteration for SE and SEZ */ c->se = 0; for (i=0; i<6; i++) c->se += mult(i2f(c->b[i] >> 2, &f), &c->dq[i]); c->sez = c->se >> 1; for (i=0; i<2; i++) c->se += mult(i2f(c->a[i] >> 2, &f), &c->sr[i]); c->se >>= 1; return av_clip(re_signal << 2, -0xffff, 0xffff); }