Add ARM64 NEON intrinsics lpc_compute_autocorrelation routines

1 files changed, 70 insertions, 0 deletions

diff --git a/src/libFLAC/deduplication/lpc_compute_autocorrelation_intrin_neon.c b/src/libFLAC/deduplication/lpc_compute_autocorrelation_intrin_neon.c
new file mode 100644
index 00000000..4df3aee9
--- /dev/null
+++ b/src/libFLAC/deduplication/lpc_compute_autocorrelation_intrin_neon.c
@@ -0,0 +1,70 @@
+	int i;
+	float64x2_t sum0 = vdupq_n_f64(0.0f);
+	float64x2_t sum1 = vdupq_n_f64(0.0f);
+	float64x2_t sum2 = vdupq_n_f64(0.0f);
+	float64x2_t sum3 = vdupq_n_f64(0.0f);
+	float64x2_t d0 = vdupq_n_f64(0.0f);
+	float64x2_t d1 = vdupq_n_f64(0.0f);
+	float64x2_t d2 = vdupq_n_f64(0.0f);
+	float64x2_t d3 = vdupq_n_f64(0.0f);
+#if MAX_LAG > 8
+	float64x2_t sum4 = vdupq_n_f64(0.0f);
+	float64x2_t d4 = vdupq_n_f64(0.0f);
+#endif
+#if MAX_LAG > 10
+	float64x2_t sum5 = vdupq_n_f64(0.0f);
+	float64x2_t sum6 = vdupq_n_f64(0.0f);
+	float64x2_t d5 = vdupq_n_f64(0.0f);
+	float64x2_t d6 = vdupq_n_f64(0.0f);
+#endif
+	float64x2_t d;
+
+	(void)lag;
+	FLAC__ASSERT(lag <= MAX_LAG);
+
+	// Loop backwards through samples from data_len to 0
+	for (i = data_len - 1; i >= 0; i--)
+	{
+		d = vdupq_n_f64(data[i]); // Create vector with 2 entries data[i]
+
+		// The next 6 lines of code right-shift the elements through the 7 vectors d0..d6.
+		// The 7th line adds the newly loaded element to d0. This works like a stack, where
+		// data[i] is pushed onto the stack every time and the 9th element falls off
+#if MAX_LAG > 10
+		d6 = vextq_f64(d5,d6,1);
+		d5 = vextq_f64(d4,d5,1);
+#endif
+#if MAX_LAG > 8
+		d4 = vextq_f64(d3,d4,1);
+#endif
+		d3 = vextq_f64(d2,d3,1);
+		d2 = vextq_f64(d1,d2,1);
+		d1 = vextq_f64(d0,d1,1);
+		d0 = vextq_f64(d,d0,1);
+
+		// Fused multiply-add sum += d * d0..d6
+		sum0 = vfmaq_f64(sum0, d, d0);
+		sum1 = vfmaq_f64(sum1, d, d1);
+		sum2 = vfmaq_f64(sum2, d, d2);
+		sum3 = vfmaq_f64(sum3, d, d3);
+#if MAX_LAG > 8
+		sum4 = vfmaq_f64(sum4, d, d4);
+#endif
+#if MAX_LAG > 10
+		sum5 = vfmaq_f64(sum5, d, d5);
+		sum6 = vfmaq_f64(sum6, d, d6);
+#endif
+	}
+
+    // Store sum0..sum6 in autoc[0..14]
+    vst1q_f64(autoc, sum0);
+    vst1q_f64(autoc + 2, sum1);
+    vst1q_f64(autoc + 4, sum2);
+    vst1q_f64(autoc + 6, sum3);
+#if MAX_LAG > 8
+    vst1q_f64(autoc + 8, sum4);
+#endif
+#if MAX_LAG > 10
+    vst1q_f64(autoc + 10, sum5);
+    vst1q_f64(autoc + 12, sum6);
+#endif