diff options
Diffstat (limited to 'ethosu/mlw_codec/mlw_decode.c')
| -rw-r--r-- | ethosu/mlw_codec/mlw_decode.c | 300 |
1 files changed, 300 insertions, 0 deletions
diff --git a/ethosu/mlw_codec/mlw_decode.c b/ethosu/mlw_codec/mlw_decode.c new file mode 100644 index 00000000..92aaea67 --- /dev/null +++ b/ethosu/mlw_codec/mlw_decode.c @@ -0,0 +1,300 @@ +/* + * Copyright (c) 2020 Arm Limited. All rights reserved. + * + * SPDX-License-Identifier: Apache-2.0 + * + * Licensed under the Apache License, Version 2.0 (the License); you may + * not use this file except in compliance with the License. + * You may obtain a copy of the License at + * + * www.apache.org/licenses/LICENSE-2.0 + * + * Unless required by applicable law or agreed to in writing, software + * distributed under the License is distributed on an AS IS BASIS, WITHOUT + * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. + * See the License for the specific language governing permissions and + * limitations under the License. + */ + +#include <stdio.h> +#include <stdlib.h> +#include <stdint.h> +#include <stdbool.h> +#include <string.h> +#include <assert.h> +#include <math.h> +#include <stdarg.h> +#include <math.h> +#include "mlw_common.h" +#include "mlw_decode.h" + + +/////////////////////////////// Read from bitstream + +typedef struct bitbuf { + uint8_t *buf; + int buf_size; // in bytes + int pos; // bit pos of next bit + int log_symbols; +} bitbuf_t; + + +// size in byte +static void bitbuf_init( bitbuf_t *bb, uint8_t *buf, int size, int log_symbols) { + bb->buf = buf; + bb->pos = 0; + bb->buf_size = size; + bb->log_symbols = log_symbols; +} + +static int bitbuf_getbit( bitbuf_t *bb) { + int byte_pos = bb->pos>>3; + int bit_pos = bb->pos&7; + if ( byte_pos < 0 || byte_pos >= bb->buf_size ) { + printf("bitbuf_getbit: underrun, bit_pos %3d byte_pos %3d buf_size %3d\n", bit_pos, byte_pos, bb->buf_size); + exit(1); + } + int bit = bb->buf[ byte_pos ] & (1<<bit_pos) ? 1 : 0; + bb->pos++; + return bit; +} + +static int bitbuf_get( bitbuf_t *bb, const char *name, int len) { + int i, data=0, save_pos=bb->pos; + if (len>0) { + for(i=0; i<len; i++) { + data |= bitbuf_getbit(bb)<<i; + } + if (bb->log_symbols) + printf("bitbuf: pos %3d %7s len %d data %x\n", save_pos, name, len, data); + } + return data; +} + +// Decode the given weight stream +// inbuf compressed bitstream +// inbuf_size size of compressed bitstream in bytes +// outbuf uncompressed 9bit signed weights, buffer malloced +// verbose if non-zero, printf log +// Return value is the number of uncompressed weights +int mlw_decode( uint8_t *inbuf, int inbuf_size, int16_t **outbuf, int verbose) { + int nvalues; + int w_grc_div; + int w_grc_trunc; + int w_uncompressed; + int z_grc_div, z_prev_grc_div=0; + int new_palette; + int palsize=0, palbits=0; + int direct_offset=0; + int16_t palette[512]; + int first=1; + int use_zero_run, i, j; + int outbuf_size=0; + int nchunks=0; + + *outbuf=0; + + bitbuf_t bitbuf_s, *bb=&bitbuf_s; + bitbuf_init( bb, inbuf, inbuf_size, (verbose&2)?1:0 ); + + // Loop over all slices + while(1) { + // Decode slice header + z_grc_div = bitbuf_get( bb, "ZDIV", 3 ); + while(z_grc_div==ZDIV_EOS) { // TODO: change to ZDIV_PAD + // End of stream + // Byte align + bitbuf_get( bb, "BYTEALIGN", (8-(bb->pos&7))&7 ); + first=1; + if ( (bb->pos/8) == inbuf_size) { + // Quit if we actually reached end of input stream + break; + } + z_grc_div = bitbuf_get( bb, "ZDIV", 3 ); + } + if ( (bb->pos/8) == inbuf_size) { + break; // reached end of input stream + } + assert(z_grc_div<4 || z_grc_div==ZDIV_DISABLE); + use_zero_run = z_grc_div!=ZDIV_DISABLE; // alternating grc + nvalues = bitbuf_get( bb, "SLICELEN", 15 )+1; + w_grc_div = bitbuf_get( bb, "WDIV", 3 ); + w_grc_trunc = bitbuf_get( bb, "WTRUNC", 1 ); + new_palette = bitbuf_get( bb, "NEWPAL", 1 ); + if (first) { + // the first slice must have a palette/direct mode setup + assert(new_palette); + first=0; + } + if (!new_palette) { + // At the moment it is not supported to change between alternating + // and non-alternating without redefining the palette (this is because + // the zero is not included in the palette in case of alternating) + int prev_use_zero_run = z_prev_grc_div!=ZDIV_DISABLE; + (void)(prev_use_zero_run); + assert( use_zero_run == prev_use_zero_run); + } + z_prev_grc_div = z_grc_div; + if (new_palette) { + direct_offset = bitbuf_get( bb, "DIROFS", 5 ); + palsize = bitbuf_get( bb, "PALSIZE", 5 ); + if (palsize>0) + palsize++; + palbits = bitbuf_get( bb, "PALBITS", 3 )+2; + for(i=0; i<palsize; i++) { + palette[i] = bitbuf_get( bb, "PALETTE", palbits ); + } + } + + if (w_grc_div==WDIV_UNCOMPRESSED) { + // Uncompressed mode + w_uncompressed = 1; + int uncompressed_bits; + if (palsize>0) { + // Uncompressed bits is given by palette size. + uncompressed_bits=0; + while( (1<<uncompressed_bits) < palsize ) + uncompressed_bits++; + } else { + // No palette. PALBITS is used to specify uncompressed bits. + uncompressed_bits=palbits; + } + // In uncompressed mode there's only a remainder part (no unary) + // This is achieved by setting w_grc_div to index bit width + w_grc_div = uncompressed_bits; + } else { + w_uncompressed = 0; + assert(w_grc_div<6); + } + + // Decode the slice + int z_nvalues = nvalues + (new_palette?1:0); + int *w_value = malloc( nvalues*sizeof(int) ); + int *z_value = malloc( z_nvalues*sizeof(int) ); + int w_pos=0, z_pos=0; + int w_prev_pos=0, z_prev_pos=0; + int w_unary0=0, w_unary1=0, w_unary1_len=0, w_q[12]={0}, w_carry=0; + int z_unary=0, z_q[12]={0}, z_carry=0; + int w_nsymbols=0; + int w_prev_enable=0, w_prev_nsymbols=0, w_prev_q[12]={0}; + int z_nsymbols=0; + int z_prev_enable=0, z_prev_nsymbols=0, z_prev_q[12]={0}; + int total_zcnt=0; + int z_unary_len = z_grc_div<3 ? 12 : 8; + + // Loop over all chunks in the slice + do { + // Flow control to possibly throttle either the weights or zero-runs + int balance = use_zero_run ? w_pos - z_pos : 0; + int w_enable = (balance<8 || !use_zero_run) && w_pos<nvalues; + int z_enable = balance>=0 && use_zero_run && z_pos<z_nvalues; + if (w_enable) { + if (!w_uncompressed) + w_unary0 = bitbuf_get( bb, "WUNARY0", 12 ); + else + w_unary0 = 0; + } + if (z_enable) { + z_unary = bitbuf_get( bb, "ZUNARY", z_unary_len ); + z_nsymbols=0; + int cnt = z_carry; + for(i=0; i<z_unary_len; i++) { + if (z_unary & (1<<i)) { + cnt++; + } else { + z_q[z_nsymbols++] = cnt; + cnt=0; + } + } + z_carry = cnt; + z_pos += z_nsymbols; + } + if (w_enable) { + w_unary1_len=0; + int max_symbols = w_uncompressed && w_grc_div>5 ? 8 : 12; + for(i=0; i<max_symbols; i++) { + if (w_unary0&(1<<i)) + w_unary1_len++; + } + w_unary1 = bitbuf_get( bb, "WUNARY1", w_unary1_len ); + w_nsymbols=0; + int cnt = w_carry; + for(i=0; i<max_symbols; i++) { + int code=0; + if (w_unary0 & (1<<i)) { + code++; + if (w_unary1&1) { + code++; + } + w_unary1 = w_unary1>>1; + } + cnt += code; + if (code<2 || w_grc_trunc) { + w_q[w_nsymbols++] = cnt; + cnt=0; + } + } + w_carry = cnt; + w_pos += w_nsymbols; + } + if (w_prev_enable) { + for(i=0; i<w_prev_nsymbols && w_prev_pos<nvalues; i++, w_prev_pos++) { + int remain = bitbuf_get( bb, "WREMAIN", w_grc_div ); + w_value[w_prev_pos] = (w_prev_q[i]<<w_grc_div) + remain; + } + } + if (z_prev_enable) { + for(i=0; i<z_prev_nsymbols && z_prev_pos<z_nvalues; i++, z_prev_pos++) { + int remain = bitbuf_get( bb, "ZREMAIN", z_grc_div ); + z_value[z_prev_pos] = (z_prev_q[i]<<z_grc_div) + remain; + total_zcnt += z_value[z_prev_pos]; + } + } + w_prev_enable = w_enable; + w_prev_nsymbols = w_nsymbols; + memcpy( w_prev_q, w_q, sizeof(w_prev_q)); + z_prev_enable = z_enable; + z_prev_nsymbols = z_nsymbols; + memcpy( z_prev_q, z_q, sizeof(z_prev_q)); + nchunks++; + } while( w_prev_enable || z_prev_enable ); + + // Interleave non-zero and zeros into the outbut buffer + // Increase the outbuffer to fit the new slice + *outbuf = realloc( *outbuf, (outbuf_size + nvalues + total_zcnt)*sizeof(int16_t)); + + int k=outbuf_size; + + // Insert initial zeros + // (slices redefining the palette may start with zeros) + if (new_palette && use_zero_run) { + for(j=0; j<z_value[0]; j++) { + (*outbuf)[k++] = 0; + } + } + + // Loop over all weights and insert zeros in-between + for(i=0; i<nvalues; i++) { + int val; + assert(w_value[i]<512); // HW supports 9bit + if (w_value[i]<palsize) { + val = palette[w_value[i]]; + } else { + val = w_value[i]-palsize+direct_offset; + } + int sign = val&1; + int mag = val>>1; + (*outbuf)[k++] = sign ? -mag : mag; + if (use_zero_run) { + for(j=0; j<z_value[i+(new_palette?1:0)]; j++) { + (*outbuf)[k++] = 0; + } + } + } + + outbuf_size = k; + free(w_value); + free(z_value); + } + return outbuf_size; +} |