constr_CHOICE.c

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/*
 * Copyright (c) 2003, 2004, 2005, 2006, 2007 Lev Walkin <vlm@lionet.info>.
 * All rights reserved.
 * Redistribution and modifications are permitted subject to BSD license.
 */
#include <asn_internal.h>
#include <constr_CHOICE.h>
#include <per_opentype.h>

/*
 * Number of bytes left for this structure.
 * (ctx->left) indicates the number of bytes _transferred_ for the structure.
 * (size) contains the number of bytes in the buffer passed.
 */
#define LEFT    ((size<(size_t)ctx->left)?size:(size_t)ctx->left)

/*
 * If the subprocessor function returns with an indication that it wants
 * more data, it may well be a fatal decoding problem, because the
 * size is constrained by the <TLV>'s L, even if the buffer size allows
 * reading more data.
 * For example, consider the buffer containing the following TLVs:
 * <T:5><L:1><V> <T:6>...
 * The TLV length clearly indicates that one byte is expected in V, but
 * if the V processor returns with "want more data" even if the buffer
 * contains way more data than the V processor have seen.
 */
#define SIZE_VIOLATION  (ctx->left >= 0 && (size_t)ctx->left <= size)

/*
 * This macro "eats" the part of the buffer which is definitely "consumed",
 * i.e. was correctly converted into local representation or rightfully skipped.
 */
#undef  ADVANCE
#define ADVANCE(num_bytes)  do {        \
        size_t num = num_bytes;     \
        ptr = ((const char *)ptr) + num;\
        size -= num;            \
        if(ctx->left >= 0)      \
            ctx->left -= num;   \
        consumed_myself += num;     \
    } while(0)

/*
 * Switch to the next phase of parsing.
 */
#undef  NEXT_PHASE
#define NEXT_PHASE(ctx) do {            \
        ctx->phase++;           \
        ctx->step = 0;          \
    } while(0)

/*
 * Return a standardized complex structure.
 */
#undef  RETURN
#define RETURN(_code)   do {            \
        rval.code = _code;      \
        rval.consumed = consumed_myself;\
        return rval;            \
    } while(0)

/*
 * See the definitions.
 */
static int _fetch_present_idx(const void *struct_ptr, int off, int size);
static void _set_present_idx(void *sptr, int offset, int size, int pres);

/*
 * Tags are canonically sorted in the tag to member table.
 */
static int
_search4tag(const void *ap, const void *bp) {
    const asn_TYPE_tag2member_t *a = (const asn_TYPE_tag2member_t *)ap;
    const asn_TYPE_tag2member_t *b = (const asn_TYPE_tag2member_t *)bp;

    int a_class = BER_TAG_CLASS(a->el_tag);
    int b_class = BER_TAG_CLASS(b->el_tag);

    if(a_class == b_class) {
        ber_tlv_tag_t a_value = BER_TAG_VALUE(a->el_tag);
        ber_tlv_tag_t b_value = BER_TAG_VALUE(b->el_tag);

        if(a_value == b_value)
            return 0;
        else if(a_value < b_value)
            return -1;
        else
            return 1;
    } else if(a_class < b_class) {
        return -1;
    } else {
        return 1;
    }
}

/*
 * The decoder of the CHOICE type.
 */
asn_dec_rval_t
CHOICE_decode_ber(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    void **struct_ptr, const void *ptr, size_t size, int tag_mode) {
    /*
     * Bring closer parts of structure description.
     */
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    asn_TYPE_member_t *elements = td->elements;

    /*
     * Parts of the structure being constructed.
     */
    void *st = *struct_ptr; /* Target structure. */
    asn_struct_ctx_t *ctx;  /* Decoder context */

    ber_tlv_tag_t tlv_tag;  /* T from TLV */
    ssize_t tag_len;    /* Length of TLV's T */
    asn_dec_rval_t rval;    /* Return code from subparsers */

    ssize_t consumed_myself = 0;    /* Consumed bytes from ptr */

    ASN_DEBUG("Decoding %s as CHOICE", td->name);

    /*
     * Create the target structure if it is not present already.
     */
    if(st == 0) {
        st = *struct_ptr = CALLOC(1, specs->struct_size);
        if(st == 0) {
            RETURN(RC_FAIL);
        }
    }

    /*
     * Restore parsing context.
     */
    ctx = (asn_struct_ctx_t *)((char *)st + specs->ctx_offset);
    
    /*
     * Start to parse where left previously
     */
    switch(ctx->phase) {
    case 0:
        /*
         * PHASE 0.
         * Check that the set of tags associated with given structure
         * perfectly fits our expectations.
         */

        if(tag_mode || td->tags_count) {
            rval = ber_check_tags(opt_codec_ctx, td, ctx, ptr, size,
                tag_mode, -1, &ctx->left, 0);
            if(rval.code != RC_OK) {
                ASN_DEBUG("%s tagging check failed: %d",
                    td->name, rval.code);
                return rval;
            }

            if(ctx->left >= 0) {
                /* ?Substracted below! */
                ctx->left += rval.consumed;
            }
            ADVANCE(rval.consumed);
        } else {
            ctx->left = -1;
        }

        NEXT_PHASE(ctx);

        ASN_DEBUG("Structure consumes %ld bytes, buffer %ld",
            (long)ctx->left, (long)size);

        /* Fall through */
    case 1:
        /*
         * Fetch the T from TLV.
         */
        tag_len = ber_fetch_tag(ptr, LEFT, &tlv_tag);
        ASN_DEBUG("In %s CHOICE tag length %d", td->name, (int)tag_len);
        switch(tag_len) {
        case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
            /* Fall through */
        case -1: RETURN(RC_FAIL);
        }

        do {
            asn_TYPE_tag2member_t *t2m;
            asn_TYPE_tag2member_t key;

            key.el_tag = tlv_tag;
            t2m = (asn_TYPE_tag2member_t *)bsearch(&key,
                    specs->tag2el, specs->tag2el_count,
                    sizeof(specs->tag2el[0]), _search4tag);
            if(t2m) {
                /*
                 * Found the element corresponding to the tag.
                 */
                NEXT_PHASE(ctx);
                ctx->step = t2m->el_no;
                break;
            } else if(specs->ext_start == -1) {
                ASN_DEBUG("Unexpected tag %s "
                    "in non-extensible CHOICE %s",
                    ber_tlv_tag_string(tlv_tag), td->name);
                RETURN(RC_FAIL);
            } else {
                /* Skip this tag */
                ssize_t skip;

                ASN_DEBUG("Skipping unknown tag %s",
                    ber_tlv_tag_string(tlv_tag));

                skip = ber_skip_length(opt_codec_ctx,
                    BER_TLV_CONSTRUCTED(ptr),
                    (const char *)ptr + tag_len,
                    LEFT - tag_len);

                switch(skip) {
                case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
                    /* Fall through */
                case -1: RETURN(RC_FAIL);
                }

                ADVANCE(skip + tag_len);
                RETURN(RC_OK);
            }
        } while(0);

    case 2:
        /*
         * PHASE 2.
         * Read in the element.
         */
        do {
        asn_TYPE_member_t *elm;/* CHOICE's element */
        void *memb_ptr;     /* Pointer to the member */
        void **memb_ptr2;   /* Pointer to that pointer */

        elm = &elements[ctx->step];

        /*
         * Compute the position of the member inside a structure,
         * and also a type of containment (it may be contained
         * as pointer or using inline inclusion).
         */
        if(elm->flags & ATF_POINTER) {
            /* Member is a pointer to another structure */
            memb_ptr2 = (void **)((char *)st + elm->memb_offset);
        } else {
            /*
             * A pointer to a pointer
             * holding the start of the structure
             */
            memb_ptr = (char *)st + elm->memb_offset;
            memb_ptr2 = &memb_ptr;
        }
        /* Set presence to be able to free it properly at any time */
        _set_present_idx(st, specs->pres_offset,
                specs->pres_size, ctx->step + 1);
        /*
         * Invoke the member fetch routine according to member's type
         */
        rval = elm->type->ber_decoder(opt_codec_ctx, elm->type,
                memb_ptr2, ptr, LEFT, elm->tag_mode);
        switch(rval.code) {
        case RC_OK:
            break;
        case RC_WMORE: /* More data expected */
            if(!SIZE_VIOLATION) {
                ADVANCE(rval.consumed);
                RETURN(RC_WMORE);
            }
            RETURN(RC_FAIL);
        case RC_FAIL: /* Fatal error */
            RETURN(rval.code);
        } /* switch(rval) */
        
        ADVANCE(rval.consumed);
      } while(0);

        NEXT_PHASE(ctx);

        /* Fall through */
    case 3:
        ASN_DEBUG("CHOICE %s Leftover: %ld, size = %ld, tm=%d, tc=%d",
            td->name, (long)ctx->left, (long)size,
            tag_mode, td->tags_count);

        if(ctx->left > 0) {
            /*
             * The type must be fully decoded
             * by the CHOICE member-specific decoder.
             */
            RETURN(RC_FAIL);
        }

        if(ctx->left == -1
        && !(tag_mode || td->tags_count)) {
            /*
             * This is an untagged CHOICE.
             * It doesn't contain nothing
             * except for the member itself, including all its tags.
             * The decoding is completed.
             */
            NEXT_PHASE(ctx);
            break;
        }

        /*
         * Read in the "end of data chunks"'s.
         */
        while(ctx->left < 0) {
            ssize_t tl;

            tl = ber_fetch_tag(ptr, LEFT, &tlv_tag);
            switch(tl) {
            case 0: if(!SIZE_VIOLATION) RETURN(RC_WMORE);
                /* Fall through */
            case -1: RETURN(RC_FAIL);
            }

            /*
             * Expected <0><0>...
             */
            if(((const uint8_t *)ptr)[0] == 0) {
                if(LEFT < 2) {
                    if(SIZE_VIOLATION)
                        RETURN(RC_FAIL);
                    else
                        RETURN(RC_WMORE);
                } else if(((const uint8_t *)ptr)[1] == 0) {
                    /*
                     * Correctly finished with <0><0>.
                     */
                    ADVANCE(2);
                    ctx->left++;
                    continue;
                }
            } else {
                ASN_DEBUG("Unexpected continuation in %s",
                    td->name);
                RETURN(RC_FAIL);
            }

            /* UNREACHABLE */
        }

        NEXT_PHASE(ctx);
    case 4:
        /* No meaningful work here */
        break;
    }
    
    RETURN(RC_OK);
}

asn_enc_rval_t
CHOICE_encode_der(asn_TYPE_descriptor_t *td, void *sptr,
        int tag_mode, ber_tlv_tag_t tag,
        asn_app_consume_bytes_f *cb, void *app_key) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    asn_TYPE_member_t *elm; /* CHOICE element */
    asn_enc_rval_t erval;
    void *memb_ptr;
    size_t computed_size = 0;
    int present;

    if(!sptr) _ASN_ENCODE_FAILED;

    ASN_DEBUG("%s %s as CHOICE",
        cb?"Encoding":"Estimating", td->name);

    present = _fetch_present_idx(sptr,
        specs->pres_offset, specs->pres_size);

    /*
     * If the structure was not initialized, it cannot be encoded:
     * can't deduce what to encode in the choice type.
     */
    if(present <= 0 || present > td->elements_count) {
        if(present == 0 && td->elements_count == 0) {
            /* The CHOICE is empty?! */
            erval.encoded = 0;
            _ASN_ENCODED_OK(erval);
        }
        _ASN_ENCODE_FAILED;
    }

    /*
     * Seek over the present member of the structure.
     */
    elm = &td->elements[present-1];
    if(elm->flags & ATF_POINTER) {
        memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
        if(memb_ptr == 0) {
            if(elm->optional) {
                erval.encoded = 0;
                _ASN_ENCODED_OK(erval);
            }
            /* Mandatory element absent */
            _ASN_ENCODE_FAILED;
        }
    } else {
        memb_ptr = (void *)((char *)sptr + elm->memb_offset);
    }

    /*
     * If the CHOICE itself is tagged EXPLICIT:
     * T ::= [2] EXPLICIT CHOICE { ... }
     * Then emit the appropriate tags.
     */
    if(tag_mode == 1 || td->tags_count) {
        /*
         * For this, we need to pre-compute the member.
         */
        ssize_t ret;

        /* Encode member with its tag */
        erval = elm->type->der_encoder(elm->type, memb_ptr,
            elm->tag_mode, elm->tag, 0, 0);
        if(erval.encoded == -1)
            return erval;

        /* Encode CHOICE with parent or my own tag */
        ret = der_write_tags(td, erval.encoded, tag_mode, 1, tag,
            cb, app_key);
        if(ret == -1)
            _ASN_ENCODE_FAILED;
        computed_size += ret;
    }

    /*
     * Encode the single underlying member.
     */
    erval = elm->type->der_encoder(elm->type, memb_ptr,
        elm->tag_mode, elm->tag, cb, app_key);
    if(erval.encoded == -1)
        return erval;

    ASN_DEBUG("Encoded CHOICE member in %ld bytes (+%ld)",
        (long)erval.encoded, (long)computed_size);

    erval.encoded += computed_size;

    return erval;
}

ber_tlv_tag_t
CHOICE_outmost_tag(asn_TYPE_descriptor_t *td, const void *ptr, int tag_mode, ber_tlv_tag_t tag) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    int present;

    assert(tag_mode == 0); (void)tag_mode;
    assert(tag == 0); (void)tag;

    /*
     * Figure out which CHOICE element is encoded.
     */
    present = _fetch_present_idx(ptr, specs->pres_offset, specs->pres_size);

    if(present > 0 || present <= td->elements_count) {
        asn_TYPE_member_t *elm = &td->elements[present-1];
        const void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(const void * const *)
                    ((const char *)ptr + elm->memb_offset);
        } else {
            memb_ptr = (const void *)
                    ((const char *)ptr + elm->memb_offset);
        }

        return asn_TYPE_outmost_tag(elm->type, memb_ptr,
            elm->tag_mode, elm->tag);
    } else {
        return (ber_tlv_tag_t)-1;
    }
}

int
CHOICE_constraint(asn_TYPE_descriptor_t *td, const void *sptr,
        asn_app_constraint_failed_f *ctfailcb, void *app_key) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    int present;

    if(!sptr) {
        _ASN_CTFAIL(app_key, td, sptr,
            "%s: value not given (%s:%d)",
            td->name, __FILE__, __LINE__);
        return -1;
    }

    /*
     * Figure out which CHOICE element is encoded.
     */
    present = _fetch_present_idx(sptr, specs->pres_offset,specs->pres_size);
    if(present > 0 && present <= td->elements_count) {
        asn_TYPE_member_t *elm = &td->elements[present-1];
        const void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(const void * const *)((const char *)sptr + elm->memb_offset);
            if(!memb_ptr) {
                if(elm->optional)
                    return 0;
                _ASN_CTFAIL(app_key, td, sptr,
                    "%s: mandatory CHOICE element %s absent (%s:%d)",
                    td->name, elm->name, __FILE__, __LINE__);
                return -1;
            }
        } else {
            memb_ptr = (const void *)((const char *)sptr + elm->memb_offset);
        }

        if(elm->memb_constraints) {
            return elm->memb_constraints(elm->type, memb_ptr,
                ctfailcb, app_key);
        } else {
            int ret = elm->type->check_constraints(elm->type,
                    memb_ptr, ctfailcb, app_key);
            /*
             * Cannot inherit it eralier:
             * need to make sure we get the updated version.
             */
            elm->memb_constraints = elm->type->check_constraints;
            return ret;
        }
    } else {
        _ASN_CTFAIL(app_key, td, sptr,
            "%s: no CHOICE element given (%s:%d)",
            td->name, __FILE__, __LINE__);
        return -1;
    }
}

#undef  XER_ADVANCE
#define XER_ADVANCE(num_bytes)  do {            \
        size_t num = num_bytes;         \
        buf_ptr = (const void *)(((const char *)buf_ptr) + num); \
        size -= num;                \
        consumed_myself += num;         \
    } while(0)

/*
 * Decode the XER (XML) data.
 */
asn_dec_rval_t
CHOICE_decode_xer(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    void **struct_ptr, const char *opt_mname,
        const void *buf_ptr, size_t size) {
    /*
     * Bring closer parts of structure description.
     */
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    const char *xml_tag = opt_mname ? opt_mname : td->xml_tag;

    /*
     * Parts of the structure being constructed.
     */
    void *st = *struct_ptr; /* Target structure. */
    asn_struct_ctx_t *ctx;  /* Decoder context */

    asn_dec_rval_t rval;        /* Return value of a decoder */
    ssize_t consumed_myself = 0;    /* Consumed bytes from ptr */
    int edx;            /* Element index */

    /*
     * Create the target structure if it is not present already.
     */
    if(st == 0) {
        st = *struct_ptr = CALLOC(1, specs->struct_size);
        if(st == 0) RETURN(RC_FAIL);
    }

    /*
     * Restore parsing context.
     */
    ctx = (asn_struct_ctx_t *)((char *)st + specs->ctx_offset);
    if(ctx->phase == 0 && !*xml_tag)
        ctx->phase = 1; /* Skip the outer tag checking phase */

    /*
     * Phases of XER/XML processing:
     * Phase 0: Check that the opening tag matches our expectations.
     * Phase 1: Processing body and reacting on closing tag.
     * Phase 2: Processing inner type.
     * Phase 3: Only waiting for closing tag.
     * Phase 4: Skipping unknown extensions.
     * Phase 5: PHASED OUT
     */
    for(edx = ctx->step; ctx->phase <= 4;) {
        pxer_chunk_type_e ch_type;  /* XER chunk type */
        ssize_t ch_size;        /* Chunk size */
        xer_check_tag_e tcv;        /* Tag check value */
        asn_TYPE_member_t *elm;

        /*
         * Go inside the member.
         */
        if(ctx->phase == 2) {
            asn_dec_rval_t tmprval;
            void *memb_ptr;     /* Pointer to the member */
            void **memb_ptr2;   /* Pointer to that pointer */

            elm = &td->elements[edx];

            if(elm->flags & ATF_POINTER) {
                /* Member is a pointer to another structure */
                memb_ptr2 = (void **)((char *)st
                    + elm->memb_offset);
            } else {
                memb_ptr = (char *)st + elm->memb_offset;
                memb_ptr2 = &memb_ptr;
            }

            /* Start/Continue decoding the inner member */
            tmprval = elm->type->xer_decoder(opt_codec_ctx,
                    elm->type, memb_ptr2, elm->name,
                    buf_ptr, size);
            XER_ADVANCE(tmprval.consumed);
            ASN_DEBUG("XER/CHOICE: itdf: [%s] code=%d",
                elm->type->name, tmprval.code);
            if(tmprval.code != RC_OK)
                RETURN(tmprval.code);
            assert(_fetch_present_idx(st,
                specs->pres_offset, specs->pres_size) == 0);
            /* Record what we've got */
            _set_present_idx(st,
                specs->pres_offset, specs->pres_size, edx + 1);
            ctx->phase = 3;
            /* Fall through */
        }

        /* No need to wait for closing tag; special mode. */
        if(ctx->phase == 3 && !*xml_tag) {
            ctx->phase = 5; /* Phase out */
            RETURN(RC_OK);
        }

        /*
         * Get the next part of the XML stream.
         */
        ch_size = xer_next_token(&ctx->context, buf_ptr, size, &ch_type);
        switch(ch_size) {
        case -1: RETURN(RC_FAIL);
        case 0:  RETURN(RC_WMORE);
        default:
            switch(ch_type) {
            case PXER_COMMENT:  /* Got XML comment */
            case PXER_TEXT:     /* Ignore free-standing text */
                XER_ADVANCE(ch_size);   /* Skip silently */
                continue;
            case PXER_TAG:
                break;  /* Check the rest down there */
            }
        }

        tcv = xer_check_tag(buf_ptr, ch_size, xml_tag);
        ASN_DEBUG("XER/CHOICE checked [%c%c%c%c] vs [%s], tcv=%d",
            ch_size>0?((const uint8_t *)buf_ptr)[0]:'?',
            ch_size>1?((const uint8_t *)buf_ptr)[1]:'?',
            ch_size>2?((const uint8_t *)buf_ptr)[2]:'?',
            ch_size>3?((const uint8_t *)buf_ptr)[3]:'?',
        xml_tag, tcv);

        /* Skip the extensions section */
        if(ctx->phase == 4) {
            ASN_DEBUG("skip_unknown(%d, %ld)",
                tcv, (long)ctx->left);
            switch(xer_skip_unknown(tcv, &ctx->left)) {
            case -1:
                ctx->phase = 5;
                RETURN(RC_FAIL);
                continue;
            case 1:
                ctx->phase = 3;
                /* Fall through */
            case 0:
                XER_ADVANCE(ch_size);
                continue;
            case 2:
                ctx->phase = 3;
                break;
            }
        }

        switch(tcv) {
        case XCT_BOTH:
            break;  /* No CHOICE? */
        case XCT_CLOSING:
            if(ctx->phase != 3)
                break;
            XER_ADVANCE(ch_size);
            ctx->phase = 5; /* Phase out */
            RETURN(RC_OK);
        case XCT_OPENING:
            if(ctx->phase == 0) {
                XER_ADVANCE(ch_size);
                ctx->phase = 1; /* Processing body phase */
                continue;
            }
            /* Fall through */
        case XCT_UNKNOWN_OP:
        case XCT_UNKNOWN_BO:

            if(ctx->phase != 1)
                break;  /* Really unexpected */

            /*
             * Search which inner member corresponds to this tag.
             */
            for(edx = 0; edx < td->elements_count; edx++) {
                elm = &td->elements[edx];
                tcv = xer_check_tag(buf_ptr,ch_size,elm->name);
                switch(tcv) {
                case XCT_BOTH:
                case XCT_OPENING:
                    /*
                     * Process this member.
                     */
                    ctx->step = edx;
                    ctx->phase = 2;
                    break;
                case XCT_UNKNOWN_OP:
                case XCT_UNKNOWN_BO:
                    continue;
                default:
                    edx = td->elements_count;
                    break;  /* Phase out */
                }
                break;
            }
            if(edx != td->elements_count)
                continue;

            /* It is expected extension */
            if(specs->ext_start != -1) {
                ASN_DEBUG("Got anticipated extension");
                /*
                 * Check for (XCT_BOTH or XCT_UNKNOWN_BO)
                 * By using a mask. Only record a pure
                 * <opening> tags.
                 */
                if(tcv & XCT_CLOSING) {
                    /* Found </extension> without body */
                    ctx->phase = 3; /* Terminating */
                } else {
                    ctx->left = 1;
                    ctx->phase = 4; /* Skip ...'s */
                }
                XER_ADVANCE(ch_size);
                continue;
            }

            /* Fall through */
        default:
            break;
        }

        ASN_DEBUG("Unexpected XML tag [%c%c%c%c] in CHOICE [%s]"
            " (ph=%d, tag=%s)",
            ch_size>0?((const uint8_t *)buf_ptr)[0]:'?',
            ch_size>1?((const uint8_t *)buf_ptr)[1]:'?',
            ch_size>2?((const uint8_t *)buf_ptr)[2]:'?',
            ch_size>3?((const uint8_t *)buf_ptr)[3]:'?',
            td->name, ctx->phase, xml_tag);
        break;
    }

    ctx->phase = 5; /* Phase out, just in case */
    RETURN(RC_FAIL);
}


asn_enc_rval_t
CHOICE_encode_xer(asn_TYPE_descriptor_t *td, void *sptr,
    int ilevel, enum xer_encoder_flags_e flags,
        asn_app_consume_bytes_f *cb, void *app_key) {
    asn_CHOICE_specifics_t *specs=(asn_CHOICE_specifics_t *)td->specifics;
    asn_enc_rval_t er;
    int present;

    if(!sptr)
        _ASN_ENCODE_FAILED;

    /*
     * Figure out which CHOICE element is encoded.
     */
    present = _fetch_present_idx(sptr, specs->pres_offset,specs->pres_size);

    if(present <= 0 || present > td->elements_count) {
        _ASN_ENCODE_FAILED;
    }  else {
        asn_enc_rval_t tmper;
        asn_TYPE_member_t *elm = &td->elements[present-1];
        void *memb_ptr;
        const char *mname = elm->name;
        unsigned int mlen = strlen(mname);

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
            if(!memb_ptr) _ASN_ENCODE_FAILED;
        } else {
            memb_ptr = (void *)((char *)sptr + elm->memb_offset);
        }

        er.encoded = 0;

                if(!(flags & XER_F_CANONICAL)) _i_ASN_TEXT_INDENT(1, ilevel);
        _ASN_CALLBACK3("<", 1, mname, mlen, ">", 1);

        tmper = elm->type->xer_encoder(elm->type, memb_ptr,
                ilevel + 1, flags, cb, app_key);
        if(tmper.encoded == -1) return tmper;

        _ASN_CALLBACK3("</", 2, mname, mlen, ">", 1);

        er.encoded += 5 + (2 * mlen) + tmper.encoded;
    }

    if(!(flags & XER_F_CANONICAL)) _i_ASN_TEXT_INDENT(1, ilevel - 1);

    _ASN_ENCODED_OK(er);
cb_failed:
    _ASN_ENCODE_FAILED;
}

asn_dec_rval_t
CHOICE_decode_uper(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td,
    asn_per_constraints_t *constraints, void **sptr, asn_per_data_t *pd) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    asn_dec_rval_t rv;
    asn_per_constraint_t *ct;
    asn_TYPE_member_t *elm; /* CHOICE's element */
    void *memb_ptr;
    void **memb_ptr2;
    void *st = *sptr;
    int value;

    if(_ASN_STACK_OVERFLOW_CHECK(opt_codec_ctx))
        _ASN_DECODE_FAILED;

    /*
     * Create the target structure if it is not present already.
     */
    if(!st) {
        st = *sptr = CALLOC(1, specs->struct_size);
        if(!st) _ASN_DECODE_FAILED;
    }

    if(constraints) ct = &constraints->value;
    else if(td->per_constraints) ct = &td->per_constraints->value;
    else ct = 0;

    if(ct && ct->flags & APC_EXTENSIBLE) {
        value = per_get_few_bits(pd, 1);
        if(value < 0) _ASN_DECODE_STARVED;
        if(value) ct = 0;   /* Not restricted */
    }

    if(ct && ct->range_bits >= 0) {
        value = per_get_few_bits(pd, ct->range_bits);
        if(value < 0) _ASN_DECODE_STARVED;
        ASN_DEBUG("CHOICE %s got index %d in range %d",
            td->name, value, ct->range_bits);
        if(value > ct->upper_bound)
            _ASN_DECODE_FAILED;
    } else {
        if(specs->ext_start == -1)
            _ASN_DECODE_FAILED;
        value = uper_get_nsnnwn(pd);
        if(value < 0) _ASN_DECODE_STARVED;
        value += specs->ext_start;
        if(value >= td->elements_count)
            _ASN_DECODE_FAILED;
    }

    /* Adjust if canonical order is different from natural order */
    if(specs->canonical_order)
        value = specs->canonical_order[value];

    /* Set presence to be able to free it later */
    _set_present_idx(st, specs->pres_offset, specs->pres_size, value + 1);

    elm = &td->elements[value];
    if(elm->flags & ATF_POINTER) {
        /* Member is a pointer to another structure */
        memb_ptr2 = (void **)((char *)st + elm->memb_offset);
    } else {
        memb_ptr = (char *)st + elm->memb_offset;
        memb_ptr2 = &memb_ptr;
    }
    ASN_DEBUG("Discovered CHOICE %s encodes %s", td->name, elm->name);

    if(ct && ct->range_bits >= 0) {
        rv = elm->type->uper_decoder(opt_codec_ctx, elm->type,
            elm->per_constraints, memb_ptr2, pd);
    } else {
        rv = uper_open_type_get(opt_codec_ctx, elm->type,
            elm->per_constraints, memb_ptr2, pd);
    }

    if(rv.code != RC_OK)
        ASN_DEBUG("Failed to decode %s in %s (CHOICE) %d",
            elm->name, td->name, rv.code);
    return rv;
}
   
asn_enc_rval_t
CHOICE_encode_uper(asn_TYPE_descriptor_t *td,
    asn_per_constraints_t *constraints, void *sptr, asn_per_outp_t *po) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    asn_TYPE_member_t *elm; /* CHOICE's element */
    asn_per_constraint_t *ct;
    void *memb_ptr;
    int present;
    int present_enc;

    if(!sptr) _ASN_ENCODE_FAILED;

    ASN_DEBUG("Encoding %s as CHOICE", td->name);

    if(constraints) ct = &constraints->value;
    else if(td->per_constraints) ct = &td->per_constraints->value;
    else ct = 0;

    present = _fetch_present_idx(sptr,
        specs->pres_offset, specs->pres_size);

    /*
     * If the structure was not initialized properly, it cannot be encoded:
     * can't deduce what to encode in the choice type.
     */
    if(present <= 0 || present > td->elements_count)
        _ASN_ENCODE_FAILED;
    else
        present--;

    ASN_DEBUG("Encoding %s CHOICE element %d", td->name, present);

    /* Adjust if canonical order is different from natural order */
    if(specs->canonical_order)
        present_enc = specs->canonical_order[present];
    else
        present_enc = present;

    if(ct && ct->range_bits >= 0) {
        if(present_enc < ct->lower_bound
        || present_enc > ct->upper_bound) {
            if(ct->flags & APC_EXTENSIBLE) {
                if(per_put_few_bits(po, 1, 1))
                    _ASN_ENCODE_FAILED;
            } else {
                _ASN_ENCODE_FAILED;
            }
            ct = 0;
        }
    }
    if(ct && ct->flags & APC_EXTENSIBLE)
        if(per_put_few_bits(po, 0, 1))
            _ASN_ENCODE_FAILED;

    elm = &td->elements[present];
    if(elm->flags & ATF_POINTER) {
        /* Member is a pointer to another structure */
        memb_ptr = *(void **)((char *)sptr + elm->memb_offset);
        if(!memb_ptr) _ASN_ENCODE_FAILED;
    } else {
        memb_ptr = (char *)sptr + elm->memb_offset;
    }

    if(ct && ct->range_bits >= 0) {
        if(per_put_few_bits(po, present_enc, ct->range_bits))
            _ASN_ENCODE_FAILED;

        return elm->type->uper_encoder(elm->type, elm->per_constraints,
            memb_ptr, po);
    } else {
        asn_enc_rval_t rval;
        if(specs->ext_start == -1)
            _ASN_ENCODE_FAILED;
        if(uper_put_nsnnwn(po, present_enc - specs->ext_start))
            _ASN_ENCODE_FAILED;
        if(uper_open_type_put(elm->type, elm->per_constraints,
            memb_ptr, po))
            _ASN_ENCODE_FAILED;
        rval.encoded = 0;
        _ASN_ENCODED_OK(rval);
    }
}
   

int
CHOICE_print(asn_TYPE_descriptor_t *td, const void *sptr, int ilevel,
        asn_app_consume_bytes_f *cb, void *app_key) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    int present;

    if(!sptr) return (cb("<absent>", 8, app_key) < 0) ? -1 : 0;

    /*
     * Figure out which CHOICE element is encoded.
     */
    present = _fetch_present_idx(sptr, specs->pres_offset,specs->pres_size);

    /*
     * Print that element.
     */
    if(present > 0 && present <= td->elements_count) {
        asn_TYPE_member_t *elm = &td->elements[present-1];
        const void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(const void * const *)((const char *)sptr + elm->memb_offset);
            if(!memb_ptr) return (cb("<absent>", 8, app_key) < 0) ? -1 : 0;
        } else {
            memb_ptr = (const void *)((const char *)sptr + elm->memb_offset);
        }

        /* Print member's name and stuff */
        if(0) {
            if(cb(elm->name, strlen(elm->name), app_key) < 0
            || cb(": ", 2, app_key) < 0)
                return -1;
        }

        return elm->type->print_struct(elm->type, memb_ptr, ilevel,
            cb, app_key);
    } else {
        return (cb("<absent>", 8, app_key) < 0) ? -1 : 0;
    }
}

void
CHOICE_free(asn_TYPE_descriptor_t *td, void *ptr, int contents_only) {
    asn_CHOICE_specifics_t *specs = (asn_CHOICE_specifics_t *)td->specifics;
    int present;

    if(!td || !ptr)
        return;

    ASN_DEBUG("Freeing %s as CHOICE", td->name);

    /*
     * Figure out which CHOICE element is encoded.
     */
    present = _fetch_present_idx(ptr, specs->pres_offset, specs->pres_size);

    /*
     * Free that element.
     */
    if(present > 0 && present <= td->elements_count) {
        asn_TYPE_member_t *elm = &td->elements[present-1];
        void *memb_ptr;

        if(elm->flags & ATF_POINTER) {
            memb_ptr = *(void **)((char *)ptr + elm->memb_offset);
            if(memb_ptr)
                ASN_STRUCT_FREE(*elm->type, memb_ptr);
        } else {
            memb_ptr = (void *)((char *)ptr + elm->memb_offset);
            ASN_STRUCT_FREE_CONTENTS_ONLY(*elm->type, memb_ptr);
        }
    }

    if(!contents_only) {
        FREEMEM(ptr);
    }
}


/*
 * The following functions functions offer protection against -fshort-enums,
 * compatible with little- and big-endian machines.
 * If assertion is triggered, either disable -fshort-enums, or add an entry
 * here with the ->pres_size of your target stracture.
 * Unless the target structure is packed, the ".present" member
 * is guaranteed to be aligned properly. ASN.1 compiler itself does not
 * produce packed code.
 */
static int
_fetch_present_idx(const void *struct_ptr, int pres_offset, int pres_size) {
    const void *present_ptr;
    int present;

    present_ptr = ((const char *)struct_ptr) + pres_offset;

    switch(pres_size) {
    case sizeof(int):   present =   *(const int *)present_ptr; break;
    case sizeof(short): present = *(const short *)present_ptr; break;
    case sizeof(char):  present =  *(const char *)present_ptr; break;
    default:
        /* ANSI C mandates enum to be equivalent to integer */
        assert(pres_size != sizeof(int));
        return 0;   /* If not aborted, pass back safe value */
    }

    return present;
}

static void
_set_present_idx(void *struct_ptr, int pres_offset, int pres_size, int present) {
    void *present_ptr;
    present_ptr = ((char *)struct_ptr) + pres_offset;

    switch(pres_size) {
    case sizeof(int):   *(int *)present_ptr   = present; break;
    case sizeof(short): *(short *)present_ptr = present; break;
    case sizeof(char):  *(char *)present_ptr  = present; break;
    default:
        /* ANSI C mandates enum to be equivalent to integer */
        assert(pres_size != sizeof(int));
    }
}