Author: cmcq
Date: Fri Jan 8 18:16:25 2010
New Revision: 5570
Log:
Save about 1KB of space using a field-to-bit lookup instead of
bit-to-field.
Modified:
amr/amrnbdata.h
amr/amrnbdec.c
Modified: amr/amrnbdata.h
==============================================================================
--- amr/amrnbdata.h Fri Jan 8 18:13:05 2010 (r5569)
+++ amr/amrnbdata.h Fri Jan 8 18:16:25 2010 (r5570)
@@ -68,15 +68,6 @@ enum Mode {
#define LP_FILTER_ORDER 10 ///< linear predictive coding filter
order
+// Each field in AMRNBFrame is stored as:
+// one byte of 16 * index in AMRNBFrame relative to previous field
+// + number of bits in the field
+// then, one byte for each bit of the field (from most-significant to
least)
+// of the position of that bit in the AMR frame.
+static const uint8_t order_MODE_4k75[] = {
+ 0x28, 7, 6, 5, 4, 3, 2, 1, 0,
+ 0x18, 15, 14, 13, 12, 11, 10, 9, 8,
+ 0x17, 51, 35, 34, 50, 33, 49, 32,
+ 0x38, 23, 22, 21, 20, 19, 18, 43, 42,
if (mode <= MODE_DTX) {
uint16_t *data = (uint16_t *)&p->frame;
- const AMROrder *order = amr_unpacking_bitmaps_per_mode[mode];
- int i;
+ const uint8_t *order = amr_unpacking_bitmaps_per_mode[mode];
+ int field_header; // 16 * relative field index + number of
field bits
memset(&p->frame, 0, sizeof(AMRNBFrame));
- for (i = 0; i < mode_bits[mode]; i++)
- data[order[i].index] += get_bits1(&gb) << order[i].bit;
+ buf++;
+ while ((field_header = *order++)) {
+ int field = 0;
+ data += field_header >> 4;
+ field_header &= 0xf;
+ while (field_header--) {
+ int bit = *order++;
+ field <<= 1;
+ field |= buf[bit >> 3] >> (bit & 7) & 1;
+ }
+ *data = field;
+ }
