Initial import of NFC GNSS SDK project

2026-09-15 16:10:12 +08:00
commit 2746cc3d4e
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+/* L3SubBand */
+
+#include "l3subband.h"
+#include "tables.h"
+#include "types.h"
+
+/*
+ * shine_subband_initialise:
+ * ----------------------
+ * Calculates the analysis filterbank coefficients and rounds to the
+ * 9th decimal place accuracy of the filterbank tables in the ISO
+ * document.  The coefficients are stored in #filter#
+ */
+void shine_subband_initialise(shine_global_config *config) {
+  int i, j;
+  double filter;
+
+  for (i = MAX_CHANNELS; i--;) {
+    config->subband.off[i] = 0;
+    memset(config->subband.x[i], 0, sizeof(config->subband.x[i]));
+  }
+
+  for (i = SBLIMIT; i--;)
+    for (j = 64; j--;) {
+      if ((filter = 1e9 * cos((double)((2 * i + 1) * (16 - j) * PI64))) >= 0)
+        modf(filter + 0.5, &filter);
+      else
+        modf(filter - 0.5, &filter);
+      /* scale and convert to fixed point before storing */
+      config->subband.fl[i][j] = (int32_t)(filter * (0x7fffffff * 1e-9));
+    }
+}
+
+/*
+ * shine_window_filter_subband:
+ * -------------------------
+ * Overlapping window on PCM samples
+ * 32 16-bit pcm samples are scaled to fractional 2's complement and
+ * concatenated to the end of the window buffer #x#. The updated window
+ * buffer #x# is then windowed by the analysis window #shine_enwindow# to
+ * produce the windowed sample #z# Calculates the analysis filter bank
+ * coefficients The windowed samples #z# is filtered by the digital filter
+ * matrix #filter# to produce the subband samples #s#. This done by first
+ * selectively picking out values from the windowed samples, and then
+ * multiplying them by the filter matrix, producing 32 subband samples.
+ */
+void shine_window_filter_subband(int16_t **buffer, int32_t s[SBLIMIT], int ch,
+                                 shine_global_config *config, int stride) {
+  int32_t y[64];
+  int i, j;
+  int16_t *ptr = *buffer;
+
+  /* replace 32 oldest samples with 32 new samples */
+  for (i = 32; i--;) {
+    config->subband.x[ch][i + config->subband.off[ch]] = ((int32_t)*ptr) << 16;
+    ptr += stride;
+  }
+  *buffer = ptr;
+
+  for (i = 64; i--;) {
+    int32_t s_value;
+#ifdef __BORLANDC__
+    uint32_t s_value_lo;
+#else
+    uint32_t s_value_lo __attribute__((unused));
+#endif
+
+    mul0(s_value, s_value_lo,
+         config->subband
+             .x[ch][(config->subband.off[ch] + i + (0 << 6)) & (HAN_SIZE - 1)],
+         shine_enwindow[i + (0 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (1 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (1 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (2 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (2 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (3 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (3 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (4 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (4 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (5 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (5 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (6 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (6 << 6)]);
+    muladd(s_value, s_value_lo,
+           config->subband.x[ch][(config->subband.off[ch] + i + (7 << 6)) &
+                                 (HAN_SIZE - 1)],
+           shine_enwindow[i + (7 << 6)]);
+    mulz(s_value, s_value_lo);
+    y[i] = s_value;
+  }
+
+  config->subband.off[ch] = (config->subband.off[ch] + 480) &
+                            (HAN_SIZE - 1); /* offset is modulo (HAN_SIZE)*/
+
+  for (i = SBLIMIT; i--;) {
+    int32_t s_value;
+#ifdef __BORLANDC__
+    uint32_t s_value_lo;
+#else
+    uint32_t s_value_lo __attribute__((unused));
+#endif
+
+    mul0(s_value, s_value_lo, config->subband.fl[i][63], y[63]);
+    for (j = 63; j; j -= 7) {
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 1], y[j - 1]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 2], y[j - 2]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 3], y[j - 3]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 4], y[j - 4]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 5], y[j - 5]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 6], y[j - 6]);
+      muladd(s_value, s_value_lo, config->subband.fl[i][j - 7], y[j - 7]);
+    }
+    mulz(s_value, s_value_lo);
+    s[i] = s_value;
+  }
+}