minor optimizations to precompute_partition_info_sums_()

diff --git a/src/libFLAC/stream_encoder.c b/src/libFLAC/stream_encoder.c
index 76173f0..5b2c12a 100644 (file)
--- a/src/libFLAC/stream_encoder.c
+++ b/src/libFLAC/stream_encoder.c
@@ -249,6 +249,7 @@ static unsigned find_best_partition_order_(
        unsigned rice_parameter,
        unsigned min_partition_order,
        unsigned max_partition_order,
+       unsigned bps,
        FLAC__bool do_escape_coding,
        unsigned rice_parameter_search_dist,
        FLAC__EntropyCodingMethod_PartitionedRice *best_partitioned_rice
@@ -260,7 +261,8 @@ static void precompute_partition_info_sums_(
        unsigned residual_samples,
        unsigned predictor_order,
        unsigned min_partition_order,
-       unsigned max_partition_order
+       unsigned max_partition_order,
+       unsigned bps
 );
 
 static void precompute_partition_info_escapes_(
@@ -3741,6 +3743,7 @@ unsigned evaluate_fixed_subframe_(
                        rice_parameter,
                        min_partition_order,
                        max_partition_order,
+                       subframe_bps,
                        do_escape_coding,
                        rice_parameter_search_dist,
                        &subframe->data.fixed.entropy_coding_method.data.partitioned_rice
@@ -3821,6 +3824,7 @@ unsigned evaluate_lpc_subframe_(
                        rice_parameter,
                        min_partition_order,
                        max_partition_order,
+                       subframe_bps,
                        do_escape_coding,
                        rice_parameter_search_dist,
                        &subframe->data.lpc.entropy_coding_method.data.partitioned_rice
@@ -3878,6 +3882,7 @@ unsigned find_best_partition_order_(
        unsigned rice_parameter,
        unsigned min_partition_order,
        unsigned max_partition_order,
+       unsigned bps,
        FLAC__bool do_escape_coding,
        unsigned rice_parameter_search_dist,
        FLAC__EntropyCodingMethod_PartitionedRice *best_partitioned_rice
@@ -3890,7 +3895,7 @@ unsigned find_best_partition_order_(
        max_partition_order = FLAC__format_get_max_rice_partition_order_from_blocksize_limited_max_and_predictor_order(max_partition_order, blocksize, predictor_order);
        min_partition_order = min(min_partition_order, max_partition_order);
 
-       precompute_partition_info_sums_(residual, abs_residual_partition_sums, residual_samples, predictor_order, min_partition_order, max_partition_order);
+       precompute_partition_info_sums_(residual, abs_residual_partition_sums, residual_samples, predictor_order, min_partition_order, max_partition_order, bps);
 
        if(do_escape_coding)
                precompute_partition_info_escapes_(residual, raw_bits_per_partition, residual_samples, predictor_order, min_partition_order, max_partition_order);
@@ -3950,56 +3955,54 @@ void precompute_partition_info_sums_(
        unsigned residual_samples,
        unsigned predictor_order,
        unsigned min_partition_order,
-       unsigned max_partition_order
+       unsigned max_partition_order,
+       unsigned bps
 )
 {
        int partition_order;
        unsigned from_partition, to_partition = 0;
        const unsigned blocksize = residual_samples + predictor_order;
+       const unsigned partitions = 1u << max_partition_order;
+       const unsigned default_partition_samples = blocksize >> max_partition_order;
+       unsigned partition, end, residual_sample;
+
+       FLAC__ASSERT(default_partition_samples > predictor_order);
 
        /* first do max_partition_order */
-       for(partition_order = (int)max_partition_order; partition_order >= 0; partition_order--) {
-               FLAC__uint64 abs_residual_partition_sum; /* OPT: can reasonably be FLAC__uint32 for bps <= 17 and maybe higher */
-               unsigned partition, partition_sample, partition_samples, residual_sample;
-               const unsigned partitions = 1u << partition_order;
-               const unsigned default_partition_samples = blocksize >> partition_order;
+       if(FLAC__bitmath_ilog2(default_partition_samples) + bps < 32) { /* very slightly pessimistic but still catches all common cases */
+               FLAC__uint32 abs_residual_partition_sum;
 
-               FLAC__ASSERT(default_partition_samples > predictor_order);
+               end = (unsigned)(-(int)predictor_order);
+               for(partition = residual_sample = 0; partition < partitions; partition++) {
+                       end += default_partition_samples;
+                       abs_residual_partition_sum = 0;
+                       for( ; residual_sample < end; residual_sample++)
+                               abs_residual_partition_sum += abs(residual[residual_sample]); /* abs(INT_MIN) is undefined, but if the residual is INT_MIN we have bigger problems */
+                       abs_residual_partition_sums[partition] = abs_residual_partition_sum;
+               }
+       }
+       else { /* have to pessimistically use 64 bits for accumulator */
+               FLAC__uint64 abs_residual_partition_sum;
 
+               end = (unsigned)(-(int)predictor_order);
                for(partition = residual_sample = 0; partition < partitions; partition++) {
-                       partition_samples = default_partition_samples;
-                       if(partition == 0)
-                               partition_samples -= predictor_order;
+                       end += default_partition_samples;
                        abs_residual_partition_sum = 0;
-                       for(partition_sample = 0; partition_sample < partition_samples; partition_sample++, residual_sample++) {
-#if defined _MSC_VER
-                               /* OPT: abs() may be faster for some compilers */
+                       for( ; residual_sample < end; residual_sample++)
                                abs_residual_partition_sum += abs(residual[residual_sample]); /* abs(INT_MIN) is undefined, but if the residual is INT_MIN we have bigger problems */
-#else
-                               const FLAC__int32 r = residual[residual_sample];
-                               if(r < 0)
-                                       abs_residual_partition_sum -= r;
-                               else
-                                       abs_residual_partition_sum += r;
-#endif
-                       }
                        abs_residual_partition_sums[partition] = abs_residual_partition_sum;
                }
-               to_partition = partitions;
-               break;
        }
 
        /* now merge partitions for lower orders */
-       for(from_partition = 0, --partition_order; partition_order >= (int)min_partition_order; partition_order--) {
-               FLAC__uint64 s;
+       for(from_partition = 0, to_partition = partitions, partition_order = (int)max_partition_order - 1; partition_order >= (int)min_partition_order; partition_order--) {
                unsigned i;
                const unsigned partitions = 1u << partition_order;
                for(i = 0; i < partitions; i++) {
-                       s = abs_residual_partition_sums[from_partition];
-                       from_partition++;
-                       abs_residual_partition_sums[to_partition] = s + abs_residual_partition_sums[from_partition];
-                       from_partition++;
-                       to_partition++;
+                       abs_residual_partition_sums[to_partition++] =
+                               abs_residual_partition_sums[from_partition  ] +
+                               abs_residual_partition_sums[from_partition+1];
+                       from_partition += 2;
                }
        }
 }