File content as of revision 0:7121d9fb45f4:

#include "mbed.h"
#include "BaseJpegDecode.h"

#if 0
#define DBG(...) do{fprintf(stderr,"[%s@%d] ",__PRETTY_FUNCTION__,__LINE__);fprintf(stderr,__VA_ARGS__);} while(0);
#define DBG_WAIT(A) wait_ms(A)
#else
#define DBG(...)
#define DBG_WAIT(A)
#endif

#define MARK_SOF 0xc0
#define MARK_DHT 0xc4
#define MARK_RST0 0xd0
#define MARK_RST7 0xd7
#define MARK_SOI 0xd8
#define MARK_EOI 0xd9
#define MARK_SOS 0xda
#define MARK_DQT 0xdb
#define MARK_DRI 0xdd
#define MARK_APP 0xe0

#define SEQ_INIT 0
#define SEQ_MARK 1
#define SEQ_LEN  2
#define SEQ_LEN2 3
#define SEQ_SKIP 4
#define SEQ_SOS  5
#define SEQ_SOS2 6

#define HT_DC 0
#define HT_AC 1

BaseJpegDecode::BaseJpegDecode()
{
    m_yblocks = JPEG_MCU_YBLOCKS; // 2 or 4
    clear();
    pHD = new HuffmanDecode;
}

void BaseJpegDecode::clear()
{
    m_seq = SEQ_INIT;
}

void BaseJpegDecode::input(uint8_t* buf, int len)
{
    for(int i = 0; i < len; i++) {
        input(buf[i]);
    }
}

void BaseJpegDecode::restart()
{
    m_block = 0;
    m_scan = 0;
    m_old_DC_value[0] = 0;
    m_old_DC_value[1] = 0;
    m_bitpat.clear();
    m_huff = NULL;
}

void BaseJpegDecode::input(uint8_t c)
{
    switch(m_seq) {
        case SEQ_INIT:
            if (c == 0xff) {
                m_seq = SEQ_MARK;
            }
            break;
        case SEQ_MARK:
            outputMARK(c);
            if (c == MARK_SOI || c == MARK_EOI) {
                m_seq = SEQ_INIT;
                break;
            }
            m_mark = c;
            m_seq = SEQ_LEN;
            break;
        case SEQ_LEN:
            m_skip = c;
            m_seq = SEQ_LEN2;
            break;
        case SEQ_LEN2:
            m_skip <<= 8;
            m_skip |= c;
            m_skip -= 2;
            m_seq = SEQ_SKIP;
            break;
        case SEQ_SKIP:
            if (--m_skip > 0) {
                break;
            }
            if (m_mark == MARK_SOS) {
                m_seq = SEQ_SOS;
                m_mcu = 0;
                restart();
                break;
            }
            m_seq = SEQ_INIT;
            break;
        case SEQ_SOS:
            if (c == 0xff) {
                m_seq = SEQ_SOS2;
                break;
            }
            inputScan(c);
            break;
        case SEQ_SOS2:
            if (c == 0x00) {
                inputScan(0xff);
                m_seq = SEQ_SOS;
                break;
            } else if (c >= MARK_RST0 && c <= MARK_RST7) {
                restart();
                m_seq = SEQ_SOS;
                break;
            }
            outputMARK(c);
            m_seq = SEQ_INIT;
            break;
        default:
            break;
    }
}

void BaseJpegDecode::inputScan(uint8_t c)
{
    m_bitpat += c;
    while(m_bitpat.size() > 0) {
        int tc = (m_scan == 0) ? HT_DC : HT_AC;
        int th = (m_block < m_yblocks) ? 0 : 1;
        DBG("%d %d %08x %d\n", tc, th, m_bitpat.peek(32), m_bitpat.size());
        if (m_huff == NULL) {
            m_huff = pHD->Lookup(tc, th, &m_bitpat);
            if (m_huff == NULL) {
                break;
            }
            m_bitpat.get(m_huff->code_size); // skip code
        }
        if (m_huff->value_size > m_bitpat.size()) {
            break;
        }
        DBG("%d %d %d %02x\n", m_huff->run, m_huff->value_size, m_huff->code_size, m_huff->code);
        int value = pHD->getValue(m_huff, &m_bitpat);
        if (tc == HT_DC) {
            value += m_old_DC_value[th];
            outputDC(m_mcu, m_block, value);
            m_old_DC_value[th] = value;
            m_scan++;
        } else { // AC
            if (m_huff->value_size == 0 && m_huff->run == 0) { // EOB
                DBG("AC EOB\n");
                m_scan = 64;
            } else {
                for(int i = 0; i < m_huff->run; i++) {
                    outputAC(m_mcu, m_block, m_scan, 0);
                    m_scan++;
                }
                outputAC(m_mcu, m_block, m_scan, value);
                m_scan++;
            }
            if (m_scan >= 64) {
                m_scan = 0;
                if (++m_block >= (m_yblocks+2)) {
                    m_block = 0;
                    m_mcu++;
                }
            }
        }
        m_huff = NULL;
    }
}