/*
 * jdinput.c
 *
 * Copyright (C) 1991-1995, Thomas G. Lane.
 * This file is part of the Independent JPEG Group's software.
 * For conditions of distribution and use, see the accompanying README file.
 *
 * This file contains input control logic for the JPEG decompressor.
 * These routines are concerned with controlling the decompressor's input
 * processing (marker reading and coefficient decoding).  The actual input
 * reading is done in jdmarker.c, jdhuff.c, and jdphuff.c.
 */

#define JPEG_INTERNALS
#include "jinclude.h"
#include "jpeglib.h"


/* Private state */

typedef struct {
    struct jpeg_input_controller pub;/* public fields */

    boolean inheaders;      /* TRUE until first SOS is reached */
} my_input_controller;

typedef my_input_controller * my_inputctl_ptr;


/* Forward declarations */
METHODDEF int consume_markers JPP( (j_decompress_ptr cinfo) );


/*
 * Routines to calculate various quantities related to the size of the image.
 */

LOCAL void
initial_setup( j_decompress_ptr cinfo ) {
/* Called once, when first SOS marker is reached */
    int ci;
    jpeg_component_info * compptr;

    /* Make sure image isn't bigger than I can handle */
    if ( ( (long) cinfo->image_height > (long) JPEG_MAX_DIMENSION ) ||
        ( (long) cinfo->image_width > (long) JPEG_MAX_DIMENSION ) ) {
        ERREXIT1( cinfo, JERR_IMAGE_TOO_BIG, (unsigned int) JPEG_MAX_DIMENSION );
    }

    /* For now, precision must match compiled-in value... */
    if ( cinfo->data_precision != BITS_IN_JSAMPLE ) {
        ERREXIT1( cinfo, JERR_BAD_PRECISION, cinfo->data_precision );
    }

    /* Check that number of components won't exceed internal array sizes */
    if ( cinfo->num_components > MAX_COMPONENTS ) {
        ERREXIT2( cinfo, JERR_COMPONENT_COUNT, cinfo->num_components,
                  MAX_COMPONENTS );
    }

    /* Compute maximum sampling factors; check factor validity */
    cinfo->max_h_samp_factor = 1;
    cinfo->max_v_samp_factor = 1;
    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        if ( ( compptr->h_samp_factor <= 0 ) || ( compptr->h_samp_factor > MAX_SAMP_FACTOR ) ||
            ( compptr->v_samp_factor <= 0 ) || ( compptr->v_samp_factor > MAX_SAMP_FACTOR ) ) {
            ERREXIT( cinfo, JERR_BAD_SAMPLING );
        }
        cinfo->max_h_samp_factor = MAX( cinfo->max_h_samp_factor,
                                        compptr->h_samp_factor );
        cinfo->max_v_samp_factor = MAX( cinfo->max_v_samp_factor,
                                        compptr->v_samp_factor );
    }

    /* We initialize DCT_scaled_size and min_DCT_scaled_size to DCTSIZE.
     * In the full decompressor, this will be overridden by jdmaster.c;
     * but in the transcoder, jdmaster.c is not used, so we must do it here.
     */
    cinfo->min_DCT_scaled_size = DCTSIZE;

    /* Compute dimensions of components */
    for ( ci = 0, compptr = cinfo->comp_info; ci < cinfo->num_components;
          ci++, compptr++ ) {
        compptr->DCT_scaled_size = DCTSIZE;
        /* Size in DCT blocks */
        compptr->width_in_blocks = (JDIMENSION)
                                   jdiv_round_up( (long) cinfo->image_width * (long) compptr->h_samp_factor,
                                                 (long) ( cinfo->max_h_samp_factor * DCTSIZE ) );
        compptr->height_in_blocks = (JDIMENSION)
                                    jdiv_round_up( (long) cinfo->image_height * (long) compptr->v_samp_factor,
                                                  (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );
        /* downsampled_width and downsampled_height will also be overridden by
         * jdmaster.c if we are doing full decompression.  The transcoder library
         * doesn't use these values, but the calling application might.
         */
        /* Size in samples */
        compptr->downsampled_width = (JDIMENSION)
                                     jdiv_round_up( (long) cinfo->image_width * (long) compptr->h_samp_factor,
                                                   (long) cinfo->max_h_samp_factor );
        compptr->downsampled_height = (JDIMENSION)
                                      jdiv_round_up( (long) cinfo->image_height * (long) compptr->v_samp_factor,
                                                    (long) cinfo->max_v_samp_factor );
        /* Mark component needed, until color conversion says otherwise */
        compptr->component_needed = TRUE;
        /* Mark no quantization table yet saved for component */
        compptr->quant_table = NULL;
    }

    /* Compute number of fully interleaved MCU rows. */
    cinfo->total_iMCU_rows = (JDIMENSION)
                             jdiv_round_up( (long) cinfo->image_height,
                                           (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );

    /* Decide whether file contains multiple scans */
    if ( ( cinfo->comps_in_scan < cinfo->num_components ) || ( cinfo->progressive_mode ) ) {
        cinfo->inputctl->has_multiple_scans = TRUE;
    } else {
        cinfo->inputctl->has_multiple_scans = FALSE;
    }
}


LOCAL void
per_scan_setup( j_decompress_ptr cinfo ) {
/* Do computations that are needed before processing a JPEG scan */
/* cinfo->comps_in_scan and cinfo->cur_comp_info[] were set from SOS marker */
    int ci, mcublks, tmp;
    jpeg_component_info * compptr;

    if ( cinfo->comps_in_scan == 1 ) {

        /* Noninterleaved (single-component) scan */
        compptr = cinfo->cur_comp_info[0];

        /* Overall image size in MCUs */
        cinfo->MCUs_per_row = compptr->width_in_blocks;
        cinfo->MCU_rows_in_scan = compptr->height_in_blocks;

        /* For noninterleaved scan, always one block per MCU */
        compptr->MCU_width = 1;
        compptr->MCU_height = 1;
        compptr->MCU_blocks = 1;
        compptr->MCU_sample_width = compptr->DCT_scaled_size;
        compptr->last_col_width = 1;
        /* For noninterleaved scans, it is convenient to define last_row_height
         * as the number of block rows present in the last iMCU row.
         */
        tmp = (int) ( compptr->height_in_blocks % compptr->v_samp_factor );
        if ( tmp == 0 ) {
            tmp = compptr->v_samp_factor;
        }
        compptr->last_row_height = tmp;

        /* Prepare array describing MCU composition */
        cinfo->blocks_in_MCU = 1;
        cinfo->MCU_membership[0] = 0;

    } else {

        /* Interleaved (multi-component) scan */
        if ( ( cinfo->comps_in_scan <= 0 ) || ( cinfo->comps_in_scan > MAX_COMPS_IN_SCAN ) ) {
            ERREXIT2( cinfo, JERR_COMPONENT_COUNT, cinfo->comps_in_scan,
                      MAX_COMPS_IN_SCAN );
        }

        /* Overall image size in MCUs */
        cinfo->MCUs_per_row = (JDIMENSION)
                              jdiv_round_up( (long) cinfo->image_width,
                                            (long) ( cinfo->max_h_samp_factor * DCTSIZE ) );
        cinfo->MCU_rows_in_scan = (JDIMENSION)
                                  jdiv_round_up( (long) cinfo->image_height,
                                                (long) ( cinfo->max_v_samp_factor * DCTSIZE ) );

        cinfo->blocks_in_MCU = 0;

        for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
            compptr = cinfo->cur_comp_info[ci];
            /* Sampling factors give # of blocks of component in each MCU */
            compptr->MCU_width = compptr->h_samp_factor;
            compptr->MCU_height = compptr->v_samp_factor;
            compptr->MCU_blocks = compptr->MCU_width * compptr->MCU_height;
            compptr->MCU_sample_width = compptr->MCU_width * compptr->DCT_scaled_size;
            /* Figure number of non-dummy blocks in last MCU column & row */
            tmp = (int) ( compptr->width_in_blocks % compptr->MCU_width );
            if ( tmp == 0 ) {
                tmp = compptr->MCU_width;
            }
            compptr->last_col_width = tmp;
            tmp = (int) ( compptr->height_in_blocks % compptr->MCU_height );
            if ( tmp == 0 ) {
                tmp = compptr->MCU_height;
            }
            compptr->last_row_height = tmp;
            /* Prepare array describing MCU composition */
            mcublks = compptr->MCU_blocks;
            if ( cinfo->blocks_in_MCU + mcublks > D_MAX_BLOCKS_IN_MCU ) {
                ERREXIT( cinfo, JERR_BAD_MCU_SIZE );
            }
            while ( mcublks-- > 0 ) {
                cinfo->MCU_membership[cinfo->blocks_in_MCU++] = ci;
            }
        }

    }
}


/*
 * Save away a copy of the Q-table referenced by each component present
 * in the current scan, unless already saved during a prior scan.
 *
 * In a multiple-scan JPEG file, the encoder could assign different components
 * the same Q-table slot number, but change table definitions between scans
 * so that each component uses a different Q-table.  (The IJG encoder is not
 * currently capable of doing this, but other encoders might.)  Since we want
 * to be able to dequantize all the components at the end of the file, this
 * means that we have to save away the table actually used for each component.
 * We do this by copying the table at the start of the first scan containing
 * the component.
 * The JPEG spec prohibits the encoder from changing the contents of a Q-table
 * slot between scans of a component using that slot.  If the encoder does so
 * anyway, this decoder will simply use the Q-table values that were current
 * at the start of the first scan for the component.
 *
 * The decompressor output side looks only at the saved quant tables,
 * not at the current Q-table slots.
 */

LOCAL void
latch_quant_tables( j_decompress_ptr cinfo ) {
    int ci, qtblno;
    jpeg_component_info * compptr;
    JQUANT_TBL * qtbl;

    for ( ci = 0; ci < cinfo->comps_in_scan; ci++ ) {
        compptr = cinfo->cur_comp_info[ci];
        /* No work if we already saved Q-table for this component */
        if ( compptr->quant_table != NULL ) {
            continue;
        }
        /* Make sure specified quantization table is present */
        qtblno = compptr->quant_tbl_no;
        if ( ( qtblno < 0 ) || ( qtblno >= NUM_QUANT_TBLS ) ||
            ( cinfo->quant_tbl_ptrs[qtblno] == NULL ) ) {
            ERREXIT1( cinfo, JERR_NO_QUANT_TABLE, qtblno );
        }
        /* OK, save away the quantization table */
        qtbl = (JQUANT_TBL *)
               ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_IMAGE,
                                            SIZEOF( JQUANT_TBL ) );
        MEMCOPY( qtbl, cinfo->quant_tbl_ptrs[qtblno], SIZEOF( JQUANT_TBL ) );
        compptr->quant_table = qtbl;
    }
}


/*
 * Initialize the input modules to read a scan of compressed data.
 * The first call to this is done by jdmaster.c after initializing
 * the entire decompressor (during jpeg_start_decompress).
 * Subsequent calls come from consume_markers, below.
 */

METHODDEF void
start_input_pass( j_decompress_ptr cinfo ) {
    per_scan_setup( cinfo );
    latch_quant_tables( cinfo );
    ( *cinfo->entropy->start_pass )( cinfo );
    ( *cinfo->coef->start_input_pass )( cinfo );
    cinfo->inputctl->consume_input = cinfo->coef->consume_data;
}


/*
 * Finish up after inputting a compressed-data scan.
 * This is called by the coefficient controller after it's read all
 * the expected data of the scan.
 */

METHODDEF void
finish_input_pass( j_decompress_ptr cinfo ) {
    cinfo->inputctl->consume_input = consume_markers;
}


/*
 * Read JPEG markers before, between, or after compressed-data scans.
 * Change state as necessary when a new scan is reached.
 * Return value is JPEG_SUSPENDED, JPEG_REACHED_SOS, or JPEG_REACHED_EOI.
 *
 * The consume_input method pointer points either here or to the
 * coefficient controller's consume_data routine, depending on whether
 * we are reading a compressed data segment or inter-segment markers.
 */

METHODDEF int
consume_markers( j_decompress_ptr cinfo ) {
    my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;
    int val;

    if ( inputctl->pub.eoi_reached ) {/* After hitting EOI, read no further */
        return JPEG_REACHED_EOI;
    }

    val = ( *cinfo->marker->read_markers )( cinfo );

    switch ( val ) {
        case JPEG_REACHED_SOS:/* Found SOS */
            if ( inputctl->inheaders ) {/* 1st SOS */
                initial_setup( cinfo );
                inputctl->inheaders = FALSE;
                /* Note: start_input_pass must be called by jdmaster.c
                 * before any more input can be consumed.  jdapi.c is
                 * responsible for enforcing this sequencing.
                 */
            } else {    /* 2nd or later SOS marker */
                if ( !inputctl->pub.has_multiple_scans ) {
                    ERREXIT( cinfo, JERR_EOI_EXPECTED );
                }                      /* Oops, I wasn't expecting this! */
                start_input_pass( cinfo );
            }
            break;
        case JPEG_REACHED_EOI:/* Found EOI */
            inputctl->pub.eoi_reached = TRUE;
            if ( inputctl->inheaders ) {/* Tables-only datastream, apparently */
                if ( cinfo->marker->saw_SOF ) {
                    ERREXIT( cinfo, JERR_SOF_NO_SOS );
                }
            } else {
                /* Prevent infinite loop in coef ctlr's decompress_data routine
                 * if user set output_scan_number larger than number of scans.
                 */
                if ( cinfo->output_scan_number > cinfo->input_scan_number ) {
                    cinfo->output_scan_number = cinfo->input_scan_number;
                }
            }
            break;
        case JPEG_SUSPENDED:
            break;
    }

    return val;
}


/*
 * Reset state to begin a fresh datastream.
 */

METHODDEF void
reset_input_controller( j_decompress_ptr cinfo ) {
    my_inputctl_ptr inputctl = (my_inputctl_ptr) cinfo->inputctl;

    inputctl->pub.consume_input = consume_markers;
    inputctl->pub.has_multiple_scans = FALSE;/* "unknown" would be better */
    inputctl->pub.eoi_reached = FALSE;
    inputctl->inheaders = TRUE;
    /* Reset other modules */
    ( *cinfo->err->reset_error_mgr )( (j_common_ptr) cinfo );
    ( *cinfo->marker->reset_marker_reader )( cinfo );
    /* Reset progression state -- would be cleaner if entropy decoder did this */
    cinfo->coef_bits = NULL;
}


/*
 * Initialize the input controller module.
 * This is called only once, when the decompression object is created.
 */

GLOBAL void
jinit_input_controller( j_decompress_ptr cinfo ) {
    my_inputctl_ptr inputctl;

    /* Create subobject in permanent pool */
    inputctl = (my_inputctl_ptr)
               ( *cinfo->mem->alloc_small )( (j_common_ptr) cinfo, JPOOL_PERMANENT,
                                            SIZEOF( my_input_controller ) );
    cinfo->inputctl = (struct jpeg_input_controller *) inputctl;
    /* Initialize method pointers */
    inputctl->pub.consume_input = consume_markers;
    inputctl->pub.reset_input_controller = reset_input_controller;
    inputctl->pub.start_input_pass = start_input_pass;
    inputctl->pub.finish_input_pass = finish_input_pass;
    /* Initialize state: can't use reset_input_controller since we don't
     * want to try to reset other modules yet.
     */
    inputctl->pub.has_multiple_scans = FALSE;/* "unknown" would be better */
    inputctl->pub.eoi_reached = FALSE;
    inputctl->inheaders = TRUE;
}