cbc_lastp
ctx->cbc_lastp = blockp;
if (ctx->cbc_lastp != NULL) {
copy_block((uint8_t *)ctx->cbc_lastp, (uint8_t *)ctx->cbc_iv);
ctx->cbc_lastp = (uint8_t *)ctx->cbc_iv;
lastp = ctx->cbc_lastp;
ctx->cbc_lastp = lastp;
ctx->cbc_lastp = lastp;
cbc_ctx->cbc_lastp = (uint8_t *)&cbc_ctx->cbc_iv[0];
cbc_ctx->cbc_lastp = (uint8_t *)&cbc_ctx->cbc_iv[0];
xor_block(cbc_ctx->cbc_lastp, M_last);
xor_block(cbc_ctx->cbc_lastp, M_last);
cbc_ctx->cbc_lastp = (uint8_t *)&(cbc_ctx->cbc_iv);
cbc_ctx->cbc_lastp = (uint8_t *)&cbc_ctx->cbc_iv[0];