mirror of https://github.com/Cisco-Talos/clamav
Steve Morgan
12 years ago
commit
bced84530b
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/*
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* Copyright (C) 2013 Sourcefire, Inc. |
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* |
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* Authors: David Raynor <draynor@sourcefire.com> |
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* |
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* This program is free software; you can redistribute it and/or modify |
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* it under the terms of the GNU General Public License version 2 as |
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* published by the Free Software Foundation. |
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* |
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* This program is distributed in the hope that it will be useful, |
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* but WITHOUT ANY WARRANTY; without even the implied warranty of |
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
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* GNU General Public License for more details. |
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* |
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* You should have received a copy of the GNU General Public License |
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* along with this program; if not, write to the Free Software |
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, |
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* MA 02110-1301, USA. |
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*/ |
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#if HAVE_CONFIG_H |
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#include "clamav-config.h" |
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#endif |
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#include <stdio.h> |
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#include <errno.h> |
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#if HAVE_STRING_H |
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#include <string.h> |
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#endif |
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#include "cltypes.h" |
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#include "others.h" |
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#include "adc.h" |
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/* #define DEBUG_ADC */ |
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#ifdef DEBUG_ADC |
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# define adc_dbgmsg(...) cli_dbgmsg( __VA_ARGS__ ) |
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#else |
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# define adc_dbgmsg(...) ; |
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#endif |
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/* Initialize values and collect buffer
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* NOTE: buffer size must be larger than largest lookback offset */ |
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int adc_decompressInit(adc_stream *strm) |
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{ |
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if (strm == NULL) { |
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return ADC_IO_ERROR; |
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} |
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if (strm->state != ADC_STATE_UNINIT) { |
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return ADC_DATA_ERROR; |
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} |
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/* Have to buffer maximum backward lookup */ |
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strm->buffer = (uint8_t *)calloc(ADC_BUFF_SIZE, 1); |
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if (strm->buffer == NULL) { |
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return ADC_MEM_ERROR; |
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} |
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strm->buffered = 0; |
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strm->state = ADC_STATE_GETTYPE; |
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strm->length = 0; |
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strm->offset = 0; |
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strm->curr = strm->buffer; |
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return ADC_OK; |
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} |
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/* Decompress routine
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* NOTE: Reaching end of input buffer does not mean end of output. |
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* It may fill the output buffer but have more to output. |
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* It will only return ADC_STREAM_END if output buffer is not full. |
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* It will return ADC_DATA_ERROR if it ends in the middle of a phrase |
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* (i.e. in the middle of a lookback code or data run) |
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*/ |
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int adc_decompress(adc_stream *strm) |
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{ |
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uint8_t bData; |
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uint8_t didNothing = 1; |
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/* first, the error returns based on strm */ |
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if ((strm == NULL) || (strm->next_in == NULL) || (strm->next_out == NULL)) { |
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return ADC_IO_ERROR; |
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} |
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if (strm->state == ADC_STATE_UNINIT) { |
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return ADC_DATA_ERROR; |
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} |
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cli_dbgmsg("adc_decompress: avail_in %lu avail_out %lu state %u\n", strm->avail_in, strm->avail_out, strm->state); |
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while (strm->avail_out) { |
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/* Exit if needs more in bytes and none available */ |
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int needsInput; |
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switch (strm->state) { |
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case ADC_STATE_SHORTLOOK: |
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case ADC_STATE_LONGLOOK: |
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needsInput = 0; |
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break; |
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default: |
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needsInput = 1; |
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break; |
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} |
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if (needsInput && (strm->avail_in == 0)) { |
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break; |
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} |
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else { |
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didNothing = 0; |
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} |
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/* Find or execute statecode */ |
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switch (strm->state) { |
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case ADC_STATE_GETTYPE: { |
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/* Grab action code */ |
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bData = *(strm->next_in); |
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strm->next_in++; |
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strm->avail_in--; |
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if (bData & 0x80) { |
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strm->state = ADC_STATE_RAWDATA; |
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strm->offset = 0; |
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strm->length = (bData & 0x7F) + 1; |
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} |
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else if (bData & 0x40) { |
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strm->state = ADC_STATE_LONGOP2; |
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strm->offset = 0; |
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strm->length = (bData & 0x3F) + 4; |
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} |
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else { |
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strm->state = ADC_STATE_SHORTOP; |
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strm->offset = (bData & 0x3) * 0x100; |
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strm->length = ((bData & 0x3C) >> 2) + 3; |
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} |
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adc_dbgmsg("adc_decompress: GETTYPE bData %x state %u offset %u length %u\n", |
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bData, strm->state, strm->offset, strm->length); |
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break; |
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} |
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case ADC_STATE_LONGOP2: { |
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/* Grab first offset byte */ |
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bData = *(strm->next_in); |
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strm->next_in++; |
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strm->avail_in--; |
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strm->offset = bData * 0x100; |
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strm->state = ADC_STATE_LONGOP1; |
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adc_dbgmsg("adc_decompress: LONGOP2 bData %x state %u offset %u length %u\n", |
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bData, strm->state, strm->offset, strm->length); |
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break; |
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} |
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case ADC_STATE_LONGOP1: { |
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/* Grab second offset byte */ |
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bData = *(strm->next_in); |
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strm->next_in++; |
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strm->avail_in--; |
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strm->offset += bData + 1; |
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strm->state = ADC_STATE_LONGLOOK; |
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adc_dbgmsg("adc_decompress: LONGOP1 bData %x state %u offset %u length %u\n", |
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bData, strm->state, strm->offset, strm->length); |
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break; |
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} |
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case ADC_STATE_SHORTOP: { |
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/* Grab offset byte */ |
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bData = *(strm->next_in); |
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strm->next_in++; |
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strm->avail_in--; |
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strm->offset += bData + 1; |
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strm->state = ADC_STATE_SHORTLOOK; |
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adc_dbgmsg("adc_decompress: SHORTOP bData %x state %u offset %u length %u\n", |
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bData, strm->state, strm->offset, strm->length); |
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break; |
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} |
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case ADC_STATE_RAWDATA: { |
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/* Grab data */ |
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adc_dbgmsg("adc_decompress: RAWDATA offset %u length %u\n", strm->offset, strm->length); |
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while ((strm->avail_in > 0) && (strm->avail_out > 0) && (strm->length > 0)) { |
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bData = *(strm->next_in); |
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strm->next_in++; |
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strm->avail_in--; |
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/* store to output */ |
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*(strm->next_out) = bData; |
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strm->next_out++; |
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strm->avail_out--; |
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/* store to buffer */ |
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if (strm->curr >= (strm->buffer + ADC_BUFF_SIZE)) { |
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strm->curr = strm->buffer; |
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} |
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*(strm->curr) = bData; |
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strm->curr++; |
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if (strm->buffered < ADC_BUFF_SIZE) { |
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strm->buffered++; |
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} |
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strm->length--; |
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} |
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if (strm->length == 0) { |
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/* adc_dbgmsg("adc_decompress: RAWDATADONE buffered %u avail_in %u avail_out %u \n",
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strm->buffered, strm->avail_in, strm->avail_out); */ |
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strm->state = ADC_STATE_GETTYPE; |
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} |
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break; |
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} |
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case ADC_STATE_SHORTLOOK: |
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case ADC_STATE_LONGLOOK: { |
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/* Copy data */ |
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adc_dbgmsg("adc_decompress: LOOKBACK offset %u length %u avail_in %u avail_out %u\n", |
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strm->offset, strm->length, strm->avail_in, strm->avail_out); |
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while ((strm->avail_out > 0) && (strm->length > 0)) { |
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/* state validation first */ |
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if (strm->offset > 0x10000) { |
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cli_dbgmsg("adc_decompress: bad LOOKBACK offset %u\n", strm->offset); |
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return ADC_DATA_ERROR; |
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} |
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else if ((strm->state == ADC_STATE_SHORTLOOK) && (strm->offset > 0x400)) { |
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cli_dbgmsg("adc_decompress: bad LOOKBACK offset %u\n", strm->offset); |
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return ADC_DATA_ERROR; |
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} |
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if (strm->offset > strm->buffered) { |
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cli_dbgmsg("adc_decompress: too large LOOKBACK offset %u\n", strm->offset); |
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return ADC_DATA_ERROR; |
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} |
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/* retrieve byte */ |
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if (strm->curr >= (strm->buffer + ADC_BUFF_SIZE)) { |
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strm->curr = strm->buffer; |
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} |
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if (strm->curr > (strm->buffer + strm->offset)) { |
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bData = *(uint8_t *)(strm->curr - strm->offset); |
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} |
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else { |
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bData = *(uint8_t *)(strm->curr + ADC_BUFF_SIZE - strm->offset); |
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} |
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/* store to output */ |
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*(strm->next_out) = bData; |
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strm->next_out++; |
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strm->avail_out--; |
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/* store to buffer */ |
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*(strm->curr) = bData; |
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strm->curr++; |
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if (strm->buffered < ADC_BUFF_SIZE) { |
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strm->buffered++; |
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} |
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strm->length--; |
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} |
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if (strm->length == 0) { |
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strm->state = ADC_STATE_GETTYPE; |
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/* adc_dbgmsg("adc_decompress: LOOKBACKDONE buffered %u avail_in %u avail_out %u \n",
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strm->buffered, strm->avail_in, strm->avail_out); */ |
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} |
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break; |
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} |
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default: { |
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/* bad state */ |
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cli_errmsg("adc_decompress: invalid state %u\n", strm->state); |
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return ADC_DATA_ERROR; |
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} |
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} /* end switch */ |
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} /* end while */ |
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/* There really isn't a terminator, just end of data */ |
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if (didNothing && strm->avail_out) { |
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if (strm->state == ADC_STATE_GETTYPE) { |
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/* Nothing left to do */ |
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return ADC_STREAM_END; |
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} |
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else { |
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/* Ended mid phrase */ |
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cli_dbgmsg("adc_decompress: stream ended mid-phrase, state %u\n", strm->state); |
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return ADC_DATA_ERROR; |
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} |
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} |
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return ADC_OK; |
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} |
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/* Cleanup routine, frees buffer */ |
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int adc_decompressEnd(adc_stream *strm) |
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{ |
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if (strm == NULL) { |
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return ADC_IO_ERROR; |
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} |
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if (strm->state == ADC_STATE_UNINIT) { |
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return ADC_DATA_ERROR; |
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} |
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if (strm->buffer != NULL) { |
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free(strm->buffer); |
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} |
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strm->buffered = 0; |
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strm->state = ADC_STATE_UNINIT; |
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strm->length = 0; |
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strm->offset = 0; |
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return ADC_OK; |
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} |
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@ -0,0 +1,55 @@ |
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#ifndef CLAM_ADC_H |
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#define CLAM_ADC_H |
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struct adc_stream { |
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uint8_t *next_in; |
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size_t avail_in; |
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size_t total_in; |
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uint8_t *next_out; |
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size_t avail_out; |
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size_t total_out; |
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/* internals */ |
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uint8_t *buffer; |
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uint8_t *curr; |
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uint32_t buffered; |
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uint16_t state; |
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uint16_t length; |
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uint32_t offset; |
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}; |
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typedef struct adc_stream adc_stream; |
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#define ADC_BUFF_SIZE 65536 |
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#define ADC_MEM_ERROR -1 |
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#define ADC_DATA_ERROR -2 |
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#define ADC_IO_ERROR -3 |
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#define ADC_OK 0 |
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#define ADC_STREAM_END 1 |
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enum adc_state { |
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ADC_STATE_UNINIT = 0, |
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ADC_STATE_GETTYPE = 1, |
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ADC_STATE_RAWDATA = 2, |
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ADC_STATE_SHORTOP = 3, |
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ADC_STATE_LONGOP2 = 4, |
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ADC_STATE_LONGOP1 = 5, |
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ADC_STATE_SHORTLOOK = 6, |
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ADC_STATE_LONGLOOK = 7 |
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}; |
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/* Compression phrases
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* store phrase - 1 byte header + data, first byte 0x80-0xFF, max length 0x80 (7 bits + 1), no offset |
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* short phrase - 2 byte header + data, first byte 0x00-0x3F, max length 0x12 (4 bits + 3), max offset 0x3FF (10 bits) |
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* long phrase - 3 byte header + data, first byte 0x40-0x7F, max length 0x43 (6 bits + 4), max offset 0xFFFF (16 bits) |
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*/ |
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int adc_decompressInit(adc_stream *strm); |
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int adc_decompress(adc_stream *strm); |
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int adc_decompressEnd(adc_stream *strm); |
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#endif |
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