Added initial AVC parser. (#176)

* * rocDecode/AVC: Added initial AVC parser.
 - Added AVC SPS, PPS and slice header parsing functions.
 - Merged common parsing code from AVC and HEVC parsers to their super class.

* * rocDecode/AVC: Formating changes. No functional changes.

src/parser/roc_video_parser.cpp

@@ -23,6 +23,7 @@ THE SOFTWARE.
 #include "roc_video_parser.h"
 
 RocVideoParser::RocVideoParser() {
+    pic_count_ = 0;
     pic_width_ = 0;
     pic_height_ = 0;
     new_sps_activated_ = false;
@@ -50,3 +51,84 @@ rocDecStatus RocVideoParser::Initialize(RocdecParserParams *pParams) {
 
     return ROCDEC_SUCCESS;
 }
+
+ParserResult RocVideoParser::GetNalUnit() {
+    bool start_code_found = false;
+
+    nal_unit_size_ = 0;
+    curr_start_code_offset_ = next_start_code_offset_;  // save the current start code offset
+
+    // Search for the next start code
+    while (curr_byte_offset_ < pic_data_size_ - 2) {
+        if (pic_data_buffer_ptr_[curr_byte_offset_] == 0 && pic_data_buffer_ptr_[curr_byte_offset_ + 1] == 0 && pic_data_buffer_ptr_[curr_byte_offset_ + 2] == 0x01) {
+            curr_start_code_offset_ = next_start_code_offset_;  // save the current start code offset
+
+            start_code_found = true;
+            start_code_num_++;
+            next_start_code_offset_ = curr_byte_offset_;
+            // Move the pointer 3 bytes forward
+            curr_byte_offset_ += 3;
+
+            // For the very first NAL unit, search for the next start code (or reach the end of frame)
+            if (start_code_num_ == 1) {
+                start_code_found = false;
+                curr_start_code_offset_ = next_start_code_offset_;
+                continue;
+            } else {
+                break;
+            }
+        }
+        curr_byte_offset_++;
+    }    
+    if (start_code_num_ == 0) {
+        // No NAL unit in the frame data
+        return PARSER_NOT_FOUND;
+    }
+    if (start_code_found) {
+        nal_unit_size_ = next_start_code_offset_ - curr_start_code_offset_;
+        return PARSER_OK;
+    } else {
+        nal_unit_size_ = pic_data_size_ - curr_start_code_offset_;
+        return PARSER_EOF;
+    }        
+}
+
+size_t RocVideoParser::EbspToRbsp(uint8_t *streamBuffer,size_t begin_bytepos, size_t end_bytepos) {
+    int count = 0;
+    if (end_bytepos < begin_bytepos) {
+        return end_bytepos;
+    }
+    uint8_t *streamBuffer_i = streamBuffer + begin_bytepos;
+    uint8_t *streamBuffer_end = streamBuffer + end_bytepos;
+    int reduce_count = 0;
+    for (; streamBuffer_i != streamBuffer_end; ) { 
+        //starting from begin_bytepos to avoid header information
+        //in NAL unit, 0x000000, 0x000001 or 0x000002 shall not occur at any uint8_t-aligned position
+        uint8_t tmp =* streamBuffer_i;
+        if (count == ZEROBYTES_SHORTSTARTCODE) {
+            if (tmp == 0x03) {
+                //check the 4th uint8_t after 0x000003, except when cabac_zero_word is used, in which case the last three bytes of this NAL unit must be 0x000003
+                if ((streamBuffer_i + 1 != streamBuffer_end) && (streamBuffer_i[1] > 0x03)) {
+                    return static_cast<size_t>(-1);
+                }
+                //if cabac_zero_word is used, the final uint8_t of this NAL unit(0x03) is discarded, and the last two bytes of RBSP must be 0x0000
+                if (streamBuffer_i + 1 == streamBuffer_end) {
+                    break;
+                }
+                memmove(streamBuffer_i, streamBuffer_i + 1, streamBuffer_end-streamBuffer_i - 1);
+                streamBuffer_end--;
+                reduce_count++;
+                count = 0;
+                tmp = *streamBuffer_i;
+            } else if (tmp < 0x03) {
+            }
+        }
+        if (tmp == 0x00) {
+            count++;
+        } else {
+            count = 0;
+        }
+        streamBuffer_i++;
+    }
+    return end_bytepos - begin_bytepos + reduce_count;
+}