/// <summary>
/// Initialize for a Huffman-compressed scan.
/// </summary>
public override void start_pass()
{
/* Validate scan parameters */
bool bad = false;
bool is_DC_band = (m_cinfo.m_Ss == 0);
if (is_DC_band)
{
if (m_cinfo.m_Se != 0)
bad = true;
}
else
{
/* need not check Ss/Se < 0 since they came from unsigned bytes */
if (m_cinfo.m_Ss > m_cinfo.m_Se || m_cinfo.m_Se >= JpegConstants.DCTSIZE2)
bad = true;
/* AC scans may have only one component */
if (m_cinfo.m_comps_in_scan != 1)
bad = true;
}
if (m_cinfo.m_Ah != 0)
{
/* Successive approximation refinement scan: must have Al = Ah-1. */
if (m_cinfo.m_Al != m_cinfo.m_Ah - 1)
bad = true;
}
if (m_cinfo.m_Al > 13)
{
/* need not check for < 0 */
bad = true;
}
/* Arguably the maximum Al value should be less than 13 for 8-bit precision,
* but the spec doesn't say so, and we try to be liberal about what we
* accept. Note: large Al values could result in out-of-range DC
* coefficients during early scans, leading to bizarre displays due to
* overflows in the IDCT math. But we won't crash.
*/
if (bad)
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_BAD_PROGRESSION, m_cinfo.m_Ss, m_cinfo.m_Se, m_cinfo.m_Ah, m_cinfo.m_Al);
/* Update progression status, and verify that scan order is legal.
* Note that inter-scan inconsistencies are treated as warnings
* not fatal errors ... not clear if this is right way to behave.
*/
for (int ci = 0; ci < m_cinfo.m_comps_in_scan; ci++)
{
int cindex = m_cinfo.Comp_info[m_cinfo.m_cur_comp_info[ci]].Component_index;
if (!is_DC_band && m_cinfo.m_coef_bits[cindex][0] < 0) /* AC without prior DC scan */
m_cinfo.WARNMS(J_MESSAGE_CODE.JWRN_BOGUS_PROGRESSION, cindex, 0);
for (int coefi = m_cinfo.m_Ss; coefi <= m_cinfo.m_Se; coefi++)
{
int expected = m_cinfo.m_coef_bits[cindex][coefi];
if (expected < 0)
expected = 0;
if (m_cinfo.m_Ah != expected)
m_cinfo.WARNMS(J_MESSAGE_CODE.JWRN_BOGUS_PROGRESSION, cindex, coefi);
m_cinfo.m_coef_bits[cindex][coefi] = m_cinfo.m_Al;
}
}
/* Select MCU decoding routine */
if (m_cinfo.m_Ah == 0)
{
if (is_DC_band)
m_decoder = MCUDecoder.mcu_DC_first_decoder;
else
m_decoder = MCUDecoder.mcu_AC_first_decoder;
}
else
{
if (is_DC_band)
m_decoder = MCUDecoder.mcu_DC_refine_decoder;
else
m_decoder = MCUDecoder.mcu_AC_refine_decoder;
}
for (int ci = 0; ci < m_cinfo.m_comps_in_scan; ci++)
{
jpeg_component_info componentInfo = m_cinfo.Comp_info[m_cinfo.m_cur_comp_info[ci]];
/* Make sure requested tables are present, and compute derived tables.
* We may build same derived table more than once, but it's not expensive.
*/
if (is_DC_band)
{
if (m_cinfo.m_Ah == 0)
{
/* DC refinement needs no table */
jpeg_make_d_derived_tbl(true, componentInfo.Dc_tbl_no, ref m_derived_tbls[componentInfo.Dc_tbl_no]);
}
}
else
{
jpeg_make_d_derived_tbl(false, componentInfo.Ac_tbl_no, ref m_derived_tbls[componentInfo.Ac_tbl_no]);
/* remember the single active table */
m_ac_derived_tbl = m_derived_tbls[componentInfo.Ac_tbl_no];
}
/* Initialize DC predictions to 0 */
m_saved.last_dc_val[ci] = 0;
}
/* Initialize bitread state variables */
m_bitstate.bits_left = 0;
m_bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
m_insufficient_data = false;
/* Initialize private state variables */
m_saved.EOBRUN = 0;
/* Initialize restart counter */
m_restarts_to_go = m_cinfo.m_restart_interval;
}
/// <summary>
/// Initialize for a Huffman-compressed scan.
/// </summary>
public override void start_pass()
{
/* Validate scan parameters */
bool bad = false;
bool is_DC_band = (m_cinfo.m_Ss == 0);
if (is_DC_band)
{
if (m_cinfo.m_Se != 0)
{
bad = true;
}
}
else
{
/* need not check Ss/Se < 0 since they came from unsigned bytes */
if (m_cinfo.m_Ss > m_cinfo.m_Se || m_cinfo.m_Se >= JpegConstants.DCTSIZE2)
{
bad = true;
}
/* AC scans may have only one component */
if (m_cinfo.m_comps_in_scan != 1)
{
bad = true;
}
}
if (m_cinfo.m_Ah != 0)
{
/* Successive approximation refinement scan: must have Al = Ah-1. */
if (m_cinfo.m_Al != m_cinfo.m_Ah - 1)
{
bad = true;
}
}
if (m_cinfo.m_Al > 13)
{
/* need not check for < 0 */
bad = true;
}
/* Arguably the maximum Al value should be less than 13 for 8-bit precision,
* but the spec doesn't say so, and we try to be liberal about what we
* accept. Note: large Al values could result in out-of-range DC
* coefficients during early scans, leading to bizarre displays due to
* overflows in the IDCT math. But we won't crash.
*/
if (bad)
{
m_cinfo.ERREXIT(J_MESSAGE_CODE.JERR_BAD_PROGRESSION, m_cinfo.m_Ss, m_cinfo.m_Se, m_cinfo.m_Ah, m_cinfo.m_Al);
}
/* Update progression status, and verify that scan order is legal.
* Note that inter-scan inconsistencies are treated as warnings
* not fatal errors ... not clear if this is right way to behave.
*/
for (int ci = 0; ci < m_cinfo.m_comps_in_scan; ci++)
{
int cindex = m_cinfo.Comp_info[m_cinfo.m_cur_comp_info[ci]].Component_index;
if (!is_DC_band && m_cinfo.m_coef_bits[cindex][0] < 0) /* AC without prior DC scan */
{
m_cinfo.WARNMS(J_MESSAGE_CODE.JWRN_BOGUS_PROGRESSION, cindex, 0);
}
for (int coefi = m_cinfo.m_Ss; coefi <= m_cinfo.m_Se; coefi++)
{
int expected = m_cinfo.m_coef_bits[cindex][coefi];
if (expected < 0)
{
expected = 0;
}
if (m_cinfo.m_Ah != expected)
{
m_cinfo.WARNMS(J_MESSAGE_CODE.JWRN_BOGUS_PROGRESSION, cindex, coefi);
}
m_cinfo.m_coef_bits[cindex][coefi] = m_cinfo.m_Al;
}
}
/* Select MCU decoding routine */
if (m_cinfo.m_Ah == 0)
{
if (is_DC_band)
{
m_decoder = MCUDecoder.mcu_DC_first_decoder;
}
else
{
m_decoder = MCUDecoder.mcu_AC_first_decoder;
}
}
else
{
if (is_DC_band)
{
m_decoder = MCUDecoder.mcu_DC_refine_decoder;
}
else
{
m_decoder = MCUDecoder.mcu_AC_refine_decoder;
}
}
for (int ci = 0; ci < m_cinfo.m_comps_in_scan; ci++)
{
jpeg_component_info componentInfo = m_cinfo.Comp_info[m_cinfo.m_cur_comp_info[ci]];
/* Make sure requested tables are present, and compute derived tables.
* We may build same derived table more than once, but it's not expensive.
*/
if (is_DC_band)
{
if (m_cinfo.m_Ah == 0)
{
/* DC refinement needs no table */
jpeg_make_d_derived_tbl(true, componentInfo.Dc_tbl_no, ref m_derived_tbls[componentInfo.Dc_tbl_no]);
}
}
else
{
jpeg_make_d_derived_tbl(false, componentInfo.Ac_tbl_no, ref m_derived_tbls[componentInfo.Ac_tbl_no]);
/* remember the single active table */
m_ac_derived_tbl = m_derived_tbls[componentInfo.Ac_tbl_no];
}
/* Initialize DC predictions to 0 */
m_saved.last_dc_val[ci] = 0;
}
/* Initialize bitread state variables */
m_bitstate.bits_left = 0;
m_bitstate.get_buffer = 0; /* unnecessary, but keeps Purify quiet */
m_insufficient_data = false;
/* Initialize private state variables */
m_saved.EOBRUN = 0;
/* Initialize restart counter */
m_restarts_to_go = m_cinfo.m_restart_interval;
}
