diff --git a/src/rspro/per_decoder.c b/src/rspro/per_decoder.c
new file mode 100644
index 0000000..20fe1a1
--- /dev/null
+++ b/src/rspro/per_decoder.c
@@ -0,0 +1,176 @@
+#include <asn_application.h>
+#include <asn_internal.h>
+#include <per_decoder.h>
+
+/*
+ * Decode a "Production of a complete encoding", X.691#10.1.
+ * The complete encoding contains at least one byte, and is an integral
+ * multiple of 8 bytes.
+ */
+asn_dec_rval_t
+uper_decode_complete(asn_codec_ctx_t *opt_codec_ctx, asn_TYPE_descriptor_t *td, void **sptr, const void *buffer, size_t size) {
+	asn_dec_rval_t rval;
+
+	rval = uper_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_complete(asn_codec_ctx_t *opt_codec_ctx, 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(((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
+uper_decode(asn_codec_ctx_t *opt_codec_ctx, 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->uper_decoder)
+		_ASN_DECODE_FAILED;	/* PER is not compiled in */
+	rval = td->uper_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 %ld, counted %ld",
+			(long)rval.consumed, (long)pd.moved);
+		assert(rval.consumed == pd.moved);
+	} else {
+		/* PER codec is not a restartable */
+		rval.consumed = 0;
+	}
+	return rval;
+}
+
+asn_dec_rval_t
+aper_decode(asn_codec_ctx_t *opt_codec_ctx, 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->aper_decoder)
+		_ASN_DECODE_FAILED;	/* PER is not compiled in */
+		rval = td->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 %d, counted %d",
+				  rval.consumed, pd.moved);
+		assert(rval.consumed == pd.moved);
+	} else {
+		/* PER codec is not a restartable */
+		rval.consumed = 0;
+	}
+	return rval;
+}