aper_decoder.c

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#include <etsi_its_cam_ts_coding/asn_application.h>
#include <etsi_its_cam_ts_coding/asn_internal.h>
#include <etsi_its_cam_ts_coding/aper_decoder.h>
 
asn_dec_rval_t
aper_decode_complete(const asn_codec_ctx_t *opt_codec_ctx,
                     const asn_TYPE_descriptor_t *td, void **sptr,
                     const void *buffer, size_t size) {
        asn_dec_rval_t rval;
 
        rval = aper_decode(opt_codec_ctx, td, sptr, buffer, size, 0, 0);
        if(rval.consumed) {
                /*
                 * We've always given 8-aligned data,
                 * so convert bits to integral bytes.
                 */
                rval.consumed += 7;
                rval.consumed >>= 3;
        } else if(rval.code == RC_OK) {
                if(size) {
                        if(((const uint8_t *)buffer)[0] == 0) {
                                rval.consumed = 1;      /* 1 byte */
                        } else {
                                ASN_DEBUG("Expecting single zeroed byte");
                                rval.code = RC_FAIL;
                        }
                } else {
                        /* Must contain at least 8 bits. */
                        rval.code = RC_WMORE;
                }
        }
 
        return rval;
}
 
asn_dec_rval_t
aper_decode(const asn_codec_ctx_t *opt_codec_ctx,
            const asn_TYPE_descriptor_t *td, void **sptr, const void *buffer,
            size_t size, int skip_bits, int unused_bits) {
        asn_codec_ctx_t s_codec_ctx;
        asn_dec_rval_t rval;
        asn_per_data_t pd;
 
        if(skip_bits < 0 || skip_bits > 7
                || unused_bits < 0 || unused_bits > 7
                || (unused_bits > 0 && !size))
                ASN__DECODE_FAILED;
 
        /*
         * Stack checker requires that the codec context
         * must be allocated on the stack.
         */
        if(opt_codec_ctx) {
                if(opt_codec_ctx->max_stack_size) {
                        s_codec_ctx = *opt_codec_ctx;
                        opt_codec_ctx = &s_codec_ctx;
                }
        } else {
                /* If context is not given, be security-conscious anyway */
                memset(&s_codec_ctx, 0, sizeof(s_codec_ctx));
                s_codec_ctx.max_stack_size = ASN__DEFAULT_STACK_MAX;
                opt_codec_ctx = &s_codec_ctx;
        }
 
        /* Fill in the position indicator */
        memset(&pd, 0, sizeof(pd));
        pd.buffer = (const uint8_t *)buffer;
        pd.nboff = skip_bits;
        pd.nbits = 8 * size - unused_bits; /* 8 is CHAR_BIT from <limits.h> */
        if(pd.nboff > pd.nbits)
                ASN__DECODE_FAILED;
 
        /*
         * Invoke type-specific decoder.
         */
        if(!td->op->aper_decoder)
                ASN__DECODE_FAILED;     /* PER is not compiled in */
        rval = td->op->aper_decoder(opt_codec_ctx, td, 0, sptr, &pd);
        if(rval.code == RC_OK) {
                /* Return the number of consumed bits */
                rval.consumed = ((pd.buffer - (const uint8_t *)buffer) << 3)
                + pd.nboff - skip_bits;
                ASN_DEBUG("PER decoding consumed %zu, counted %zu",
                                  rval.consumed, pd.moved);
                assert(rval.consumed == pd.moved);
        } else {
                /* PER codec is not a restartable */
                rval.consumed = 0;
        }
        return rval;
}