programming/glk/gi_blorb.c

/* gi_blorb.c: Blorb library layer for Glk API.
    gi_blorb version 1.6.1.
    Designed by Andrew Plotkin <erkyrath@eblong.com>
    http://eblong.com/zarf/glk/

    This file is copyright 1998-2017 by Andrew Plotkin. It is
    distributed under the MIT license; see the "LICENSE" file.
*/

#include "glk.h"
#include "gi_blorb.h"

#ifndef NULL
#define NULL 0
#endif
#ifndef TRUE
#define TRUE 1
#endif
#ifndef FALSE
#define FALSE 0
#endif

/* The magic macro of endian conversion. */

#define giblorb_native4(v)   \
    ( (((glui32)((v)[3])      ) & 0x000000ff)    \
    | (((glui32)((v)[2]) <<  8) & 0x0000ff00)    \
    | (((glui32)((v)[1]) << 16) & 0x00ff0000)    \
    | (((glui32)((v)[0]) << 24) & 0xff000000))

/* More four-byte constants. */

#define giblorb_ID_FORM (giblorb_make_id('F', 'O', 'R', 'M'))
#define giblorb_ID_IFRS (giblorb_make_id('I', 'F', 'R', 'S'))
#define giblorb_ID_RIdx (giblorb_make_id('R', 'I', 'd', 'x'))

/* giblorb_chunkdesc_t: Describes one chunk of the Blorb file. */
typedef struct giblorb_chunkdesc_struct {
    glui32 type;
    glui32 len;
    glui32 startpos; /* start of chunk header */
    glui32 datpos; /* start of data (either startpos or startpos+8) */
    
    void *ptr; /* pointer to malloc'd data, if loaded */
    int auxdatnum; /* entry in the auxsound/auxpict array; -1 if none.
        This only applies to chunks that represent resources. 
        (Currently, only images.) */
    
} giblorb_chunkdesc_t;

/* giblorb_resdesc_t: Describes one resource in the Blorb file. */
typedef struct giblorb_resdesc_struct {
    glui32 usage;
    glui32 resnum;
    glui32 chunknum;
} giblorb_resdesc_t;

/* giblorb_auxpict_t: Extra information about an image. */
typedef struct giblorb_auxpict_struct {
    int loaded;
    glui32 width;
    glui32 height;
    char *alttext;
} giblorb_auxpict_t;

/* giblorb_map_t: Holds the complete description of an open Blorb file. */
struct giblorb_map_struct {
    glui32 inited; /* holds giblorb_Inited_Magic if the map structure is 
        valid */
    strid_t file;
    
    int numchunks;
    giblorb_chunkdesc_t *chunks; /* list of chunk descriptors */
    
    int numresources;
    giblorb_resdesc_t *resources; /* list of resource descriptors */
    giblorb_resdesc_t **ressorted; /* list of pointers to descriptors 
        in map->resources -- sorted by usage and resource number. */

    giblorb_auxpict_t *auxpict;
};

#define giblorb_Inited_Magic (0xB7012BED) 

/* Static variables. */

static int lib_inited = FALSE;

static giblorb_err_t giblorb_initialize(void);
static giblorb_err_t giblorb_initialize_map(giblorb_map_t *map);
static giblorb_err_t giblorb_image_get_size_jpeg(unsigned char *ptr, glui32 length, giblorb_auxpict_t *auxpict);
static giblorb_err_t giblorb_image_get_size_png(unsigned char *ptr, glui32 length, giblorb_auxpict_t *auxpict);
static void giblorb_qsort(giblorb_resdesc_t **list, int len);
static giblorb_resdesc_t *giblorb_bsearch(giblorb_resdesc_t *sample, 
    giblorb_resdesc_t **list, int len);
static void *giblorb_malloc(glui32 len);
static void *giblorb_realloc(void *ptr, glui32 len);
static void giblorb_free(void *ptr);

static giblorb_err_t giblorb_initialize()
{
    return giblorb_err_None;
}

giblorb_err_t giblorb_create_map(strid_t file, giblorb_map_t **newmap)
{
    giblorb_err_t err;
    giblorb_map_t *map;
    glui32 readlen;
    glui32 nextpos, totallength;
    giblorb_chunkdesc_t *chunks;
    int chunks_size, numchunks;
    char buffer[16];
    
    *newmap = NULL;
    
    if (!lib_inited) {
        err = giblorb_initialize();
        if (err)
            return err;
        lib_inited = TRUE;
    }

    /* First, chew through the file and index the chunks. */
    
    glk_stream_set_position(file, 0, seekmode_Start);
    
    readlen = glk_get_buffer_stream(file, buffer, 12);
    if (readlen != 12)
        return giblorb_err_Read;
    
    if (giblorb_native4(buffer+0) != giblorb_ID_FORM)
        return giblorb_err_Format;
    if (giblorb_native4(buffer+8) != giblorb_ID_IFRS)
        return giblorb_err_Format;
    
    totallength = giblorb_native4(buffer+4) + 8;
    nextpos = 12;

    chunks_size = 8;
    numchunks = 0;
    chunks = (giblorb_chunkdesc_t *)giblorb_malloc(sizeof(giblorb_chunkdesc_t) 
        * chunks_size);

    while (nextpos < totallength) {
        glui32 type, len;
        int chunum;
        giblorb_chunkdesc_t *chu;
        
        glk_stream_set_position(file, nextpos, seekmode_Start);
        
        readlen = glk_get_buffer_stream(file, buffer, 8);
        if (readlen != 8) {
            giblorb_free(chunks);
            return giblorb_err_Read;
        }
        
        type = giblorb_native4(buffer+0);
        len = giblorb_native4(buffer+4);
        
        if (numchunks >= chunks_size) {
            chunks_size *= 2;
            chunks = (giblorb_chunkdesc_t *)giblorb_realloc(chunks, 
                sizeof(giblorb_chunkdesc_t) * chunks_size);
        }
        
        chunum = numchunks;
        chu = &(chunks[chunum]);
        numchunks++;
        
        chu->type = type;
        chu->startpos = nextpos;
        if (type == giblorb_ID_FORM) {
            chu->datpos = nextpos;
            chu->len = len+8;
        }
        else {
            chu->datpos = nextpos+8;
            chu->len = len;
        }
        chu->ptr = NULL;
        chu->auxdatnum = -1;
        
        nextpos = nextpos + len + 8;
        if (nextpos & 1)
            nextpos++;
            
        if (nextpos > totallength) {
            giblorb_free(chunks);
            return giblorb_err_Format;
        }
    }
    
    /* The basic IFF structure seems to be ok, and we have a list of
        chunks. Now we allocate the map structure itself. */
    
    map = (giblorb_map_t *)giblorb_malloc(sizeof(giblorb_map_t));
    if (!map) {
        giblorb_free(chunks);
        return giblorb_err_Alloc;
    }
        
    map->inited = giblorb_Inited_Magic;
    map->file = file;
    map->chunks = chunks;
    map->numchunks = numchunks;
    map->resources = NULL;
    map->ressorted = NULL;
    map->numresources = 0;
    /*map->releasenum = 0;
    map->zheader = NULL;
    map->resolution = NULL;
    map->palettechunk = -1;
    map->palette = NULL;
    map->auxsound = NULL;*/
    map->auxpict = NULL;
    
    /* Now we do everything else involved in loading the Blorb file,
        such as building resource lists. */
    
    err = giblorb_initialize_map(map);
    if (err) {
        giblorb_destroy_map(map);
        return err;
    }
    
    *newmap = map;
    return giblorb_err_None;
}

static giblorb_err_t giblorb_initialize_map(giblorb_map_t *map)
{
    /* It is important that the map structure be kept valid during this
        function. If this returns an error, giblorb_destroy_map() will 
        be called. */
        
    int ix, jx;
    giblorb_result_t chunkres;
    giblorb_err_t err;
    char *ptr;
    glui32 len;
    glui32 numres;
    int gotindex = FALSE;
    int pictcount = 0;

    for (ix=0; ix<map->numchunks; ix++) {
        giblorb_chunkdesc_t *chu = &map->chunks[ix];
        
        switch (chu->type) {
        
            case giblorb_ID_RIdx:
                /* Resource index chunk: build the resource list and 
                sort it. */
                
                if (gotindex) 
                    return giblorb_err_Format; /* duplicate index chunk */
                err = giblorb_load_chunk_by_number(map, giblorb_method_Memory, 
                    &chunkres, ix);
                if (err) 
                    return err;
                
                ptr = chunkres.data.ptr;
                len = chunkres.length;
                numres = giblorb_native4(ptr+0);

                if (numres & 0xF0000000)
                    return giblorb_err_Format; /* that can't be right */

                if (numres) {
                    int ix2;
                    giblorb_resdesc_t *resources = NULL;
                    giblorb_resdesc_t **ressorted = NULL;
                    
                    if (len != numres*12+4)
                        return giblorb_err_Format; /* bad length field */
                    
                    resources = (giblorb_resdesc_t *)giblorb_malloc(numres 
                        * sizeof(giblorb_resdesc_t));
                    if (!resources) {
                        return giblorb_err_Alloc;
                    }
                    ressorted = (giblorb_resdesc_t **)giblorb_malloc(numres 
                        * sizeof(giblorb_resdesc_t *));
                    if (!ressorted) {
                        giblorb_free(resources);
                        return giblorb_err_Alloc;
                    }
                    
                    ix2 = 0;
                    for (jx=0; jx<numres; jx++) {
                        giblorb_resdesc_t *res = &(resources[jx]);
                        glui32 respos;
                        
                        res->usage = giblorb_native4(ptr+jx*12+4);
                        res->resnum = giblorb_native4(ptr+jx*12+8);
                        respos = giblorb_native4(ptr+jx*12+12);
                        
                        while (ix2 < map->numchunks 
                            && map->chunks[ix2].startpos < respos)
                            ix2++;
                        
                        if (ix2 >= map->numchunks 
                            || map->chunks[ix2].startpos != respos) {
                            /* start pos does not match a real chunk */
                            giblorb_free(resources);
                            giblorb_free(ressorted);
                            return giblorb_err_Format;
                        }
                        
                        res->chunknum = ix2;
                        
                        ressorted[jx] = res;
                    }
                    
                    /* Sort a resource list (actually a list of pointers to 
                        structures in map->resources.) This makes it easy 
                        to find resources by usage and resource number. */
                    giblorb_qsort(ressorted, numres);
                    
                    map->numresources = numres;
                    map->resources = resources;
                    map->ressorted = ressorted;
                }
                
                giblorb_unload_chunk(map, ix);
                gotindex = TRUE;
                break;

            case giblorb_ID_JPEG:
            case giblorb_ID_PNG:
                chu->auxdatnum = pictcount;
                pictcount++;
                break;
            
        }
    }

    if (pictcount) {
        map->auxpict = (giblorb_auxpict_t *)giblorb_malloc(pictcount 
            * sizeof(giblorb_auxpict_t));
        if (!map->auxpict)
            return giblorb_err_Alloc;
        for (ix=0; ix<pictcount; ix++) {
            giblorb_auxpict_t *auxpict = &(map->auxpict[ix]);
            auxpict->loaded = FALSE;
            auxpict->width = 0;
            auxpict->height = 0;
            auxpict->alttext = NULL;
        }
    }
    
    return giblorb_err_None;
}

giblorb_err_t giblorb_destroy_map(giblorb_map_t *map)
{
    int ix;
    
    if (!map || !map->chunks || map->inited != giblorb_Inited_Magic)
        return giblorb_err_NotAMap;

    if (map->auxpict) {
        giblorb_free(map->auxpict);
        map->auxpict = NULL;
    }
    
    for (ix=0; ix<map->numchunks; ix++) {
        giblorb_chunkdesc_t *chu = &(map->chunks[ix]);
        if (chu->ptr) {
            giblorb_free(chu->ptr);
            chu->ptr = NULL;
        }
    }
    
    if (map->chunks) {
        giblorb_free(map->chunks);
        map->chunks = NULL;
    }
    
    map->numchunks = 0;
    
    if (map->resources) {
        giblorb_free(map->resources);
        map->resources = NULL;
    }
    
    if (map->ressorted) {
        giblorb_free(map->ressorted);
        map->ressorted = NULL;
    }
    
    map->numresources = 0;
    
    map->file = NULL;
    map->inited = 0;
    
    giblorb_free(map);

    return giblorb_err_None;
}

/* Chunk-handling functions. */

giblorb_err_t giblorb_load_chunk_by_type(giblorb_map_t *map, 
    glui32 method, giblorb_result_t *res, glui32 type, 
    glui32 count)
{
    int ix;
    
    for (ix=0; ix < map->numchunks; ix++) {
        if (map->chunks[ix].type == type) {
            if (count == 0)
                break;
            count--;
        }
    }
    
    if (ix >= map->numchunks) {
        return giblorb_err_NotFound;
    }
    
    return giblorb_load_chunk_by_number(map, method, res, ix);
}

giblorb_err_t giblorb_load_chunk_by_number(giblorb_map_t *map, 
    glui32 method, giblorb_result_t *res, glui32 chunknum)
{
    giblorb_chunkdesc_t *chu;
    
    if (chunknum >= map->numchunks)
        return giblorb_err_NotFound;

    chu = &(map->chunks[chunknum]);
    
    switch (method) {
    
        case giblorb_method_DontLoad:
            /* do nothing */
            break;
            
        case giblorb_method_FilePos:
            res->data.startpos = chu->datpos;
            break;
            
        case giblorb_method_Memory:
            if (!chu->ptr) {
                glui32 readlen;
                void *dat = giblorb_malloc(chu->len);
                
                if (!dat)
                    return giblorb_err_Alloc;
                
                glk_stream_set_position(map->file, chu->datpos, 
                    seekmode_Start);
                
                readlen = glk_get_buffer_stream(map->file, dat, 
                    chu->len);
                if (readlen != chu->len)
                    return giblorb_err_Read;
                
                chu->ptr = dat;
            }
            res->data.ptr = chu->ptr;
            break;
    }
    
    res->chunknum = chunknum;
    res->length = chu->len;
    res->chunktype = chu->type;
    
    return giblorb_err_None;
}

giblorb_err_t giblorb_load_resource(giblorb_map_t *map, glui32 method, 
    giblorb_result_t *res, glui32 usage, glui32 resnum)
{
    giblorb_resdesc_t sample;
    giblorb_resdesc_t *found;
    
    sample.usage = usage;
    sample.resnum = resnum;
    
    found = giblorb_bsearch(&sample, map->ressorted, map->numresources);
    
    if (!found)
        return giblorb_err_NotFound;
    
    return giblorb_load_chunk_by_number(map, method, res, found->chunknum);
}

giblorb_err_t giblorb_unload_chunk(giblorb_map_t *map, glui32 chunknum)
{
    giblorb_chunkdesc_t *chu;
    
    if (chunknum >= map->numchunks)
        return giblorb_err_NotFound;

    chu = &(map->chunks[chunknum]);
    
    if (chu->ptr) {
        giblorb_free(chu->ptr);
        chu->ptr = NULL;
    }
    
    return giblorb_err_None;
}

giblorb_err_t giblorb_count_resources(giblorb_map_t *map, glui32 usage,
    glui32 *num, glui32 *min, glui32 *max)
{
    int ix;
    int count;
    glui32 val;
    glui32 minval, maxval;
    
    count = 0;
    minval = 0;
    maxval = 0;
    
    for (ix=0; ix<map->numresources; ix++) {
        if (map->resources[ix].usage == usage) {
            val = map->resources[ix].resnum;
            if (count == 0) {
                count++;
                minval = val;
                maxval = val;
            }
            else {
                count++;
                if (val < minval)
                    minval = val;
                if (val > maxval)
                    maxval = val;
            }
        }
    }
    
    if (num)
        *num = count;
    if (min)
        *min = minval;
    if (max)
        *max = maxval;
    
    return giblorb_err_None;
}

giblorb_err_t giblorb_load_image_info(giblorb_map_t *map,
    glui32 resnum, giblorb_image_info_t *res)
{
    giblorb_resdesc_t sample;
    giblorb_resdesc_t *found;
    glui32 chunknum;
    giblorb_chunkdesc_t *chu;
    giblorb_auxpict_t *auxpict;
    
    sample.usage = giblorb_ID_Pict;
    sample.resnum = resnum;
    
    found = giblorb_bsearch(&sample, map->ressorted, map->numresources);
    
    if (!found)
        return giblorb_err_NotFound;
    
    chunknum = found->chunknum;
    if (chunknum >= map->numchunks)
        return giblorb_err_NotFound;

    chu = &(map->chunks[chunknum]);
    if (chu->auxdatnum < 0)
        return giblorb_err_NotFound;

    auxpict = &(map->auxpict[chu->auxdatnum]);
    if (!auxpict->loaded) {
        giblorb_result_t res;
        giblorb_err_t err = giblorb_load_chunk_by_number(map, giblorb_method_Memory, &res, chunknum);
        if (err)
            return err;

        if (chu->type == giblorb_ID_JPEG)
            err = giblorb_image_get_size_jpeg(res.data.ptr, res.length, auxpict);
        else if (chu->type == giblorb_ID_PNG)
            err = giblorb_image_get_size_png(res.data.ptr, res.length, auxpict);
        else
            err = giblorb_err_Format;

        giblorb_unload_chunk(map, chunknum);

        if (err)
            return err;

        auxpict->loaded = TRUE;
    }

    res->chunktype = chu->type;
    res->width = auxpict->width;
    res->height = auxpict->height;
    res->alttext = auxpict->alttext;
    return giblorb_err_None;
}

static giblorb_err_t giblorb_image_get_size_jpeg(unsigned char *arr, glui32 length, giblorb_auxpict_t *auxpict)
{
    int pos = 0;
    while (pos < length) {
        unsigned char marker;
        int chunklen;
        if (arr[pos] != 0xFF) {
            /* error: find_dimensions_jpeg: marker is not 0xFF */
            return giblorb_err_Format;
        }
        while (arr[pos] == 0xFF) 
            pos += 1;
        marker = arr[pos];
        pos += 1;
        if (marker == 0x01 || (marker >= 0xD0 && marker <= 0xD9)) {
            /* marker type has no data */
            continue;
        }
        chunklen = (arr[pos+0] << 8) | (arr[pos+1]);
        if (marker >= 0xC0 && marker <= 0xCF && marker != 0xC8) {
            if (chunklen < 7) {
                /* error: find_dimensions_jpeg: SOF block is too small */
                return giblorb_err_Format;
            }
            auxpict->height = (arr[pos+3] << 8) | (arr[pos+4]);
            auxpict->width  = (arr[pos+5] << 8) | (arr[pos+6]);
            return giblorb_err_None;
        }
        pos += chunklen;
    }

    /* error: find_dimensions_jpeg: no SOF marker found */
    return giblorb_err_Format;
}

static giblorb_err_t giblorb_image_get_size_png(unsigned char *arr, glui32 length, giblorb_auxpict_t *auxpict)
{
    int pos = 0;
    if (length < 8)
        return giblorb_err_Format;
    if (arr[0] != 0x89 || arr[1] != 'P' || arr[2] != 'N' || arr[3] != 'G') {
        /* error: find_dimensions_png: PNG signature does not match */
        return giblorb_err_Format;
    }
    pos += 8;
    while (pos < length) {
        glui32 chunklen = giblorb_native4(arr+pos);
        glui32 chunktype;
        pos += 4;
        chunktype = giblorb_native4(arr+pos);
        pos += 4;
        if (chunktype == giblorb_make_id('I', 'H', 'D', 'R')) {
            auxpict->width = giblorb_native4(arr+pos);
            pos += 4;
            auxpict->height = giblorb_native4(arr+pos);
            pos += 4;
            return giblorb_err_None;
        }
        pos += chunklen;
        pos += 4; /* skip CRC */
    }

    /* error: find_dimensions_png: no PNG header block found */
    return giblorb_err_Format;
}

/* Sorting and searching. */

static int sortsplot(giblorb_resdesc_t *v1, giblorb_resdesc_t *v2)
{
    if (v1->usage < v2->usage)
        return -1;
    if (v1->usage > v2->usage)
        return 1;
    if (v1->resnum < v2->resnum)
        return -1;
    if (v1->resnum > v2->resnum)
        return 1;
    return 0;
}

static void giblorb_qsort(giblorb_resdesc_t **list, int len)
{
    int ix, jx, res;
    giblorb_resdesc_t *tmpptr, *pivot;
    
    if (len < 6) {
        /* The list is short enough for a bubble-sort. */
        for (jx=len-1; jx>0; jx--) {
            for (ix=0; ix<jx; ix++) {
                res = sortsplot(list[ix], list[ix+1]);
                if (res > 0) {
                    tmpptr = list[ix];
                    list[ix] = list[ix+1];
                    list[ix+1] = tmpptr;
                }
            }
        }
    }
    else {
        /* Split the list. */
        pivot = list[len/2];
        ix=0;
        jx=len;
        while (1) {
            while (ix < jx-1 && sortsplot(list[ix], pivot) < 0)
                ix++;
            while (ix < jx-1 && sortsplot(list[jx-1], pivot) > 0)
                jx--;
            if (ix >= jx-1)
                break;
            tmpptr = list[ix];
            list[ix] = list[jx-1];
            list[jx-1] = tmpptr;
        }
        ix++;
        /* Sort the halves. */
        giblorb_qsort(list+0, ix);
        giblorb_qsort(list+ix, len-ix);
    }
}

giblorb_resdesc_t *giblorb_bsearch(giblorb_resdesc_t *sample, 
    giblorb_resdesc_t **list, int len)
{
    int top, bot, val, res;
    
    bot = 0;
    top = len;
    
    while (bot < top) {
        val = (top+bot) / 2;
        res = sortsplot(list[val], sample);
        if (res == 0)
            return list[val];
        if (res < 0) {
            bot = val+1;
        }
        else {
            top = val;
        }
    }
    
    return NULL;
}


/* Boring utility functions. If your platform doesn't support ANSI 
    malloc(), feel free to edit these however you like. */

#include <stdlib.h> /* The OS-native header file -- you can edit 
    this too. */

static void *giblorb_malloc(glui32 len)
{
    return malloc(len);
}

static void *giblorb_realloc(void *ptr, glui32 len)
{
    return realloc(ptr, len);
}

static void giblorb_free(void *ptr)
{
    free(ptr);
}