X-Git-Url: https://git.stg.codes/stg.git/blobdiff_plain/87550f881db0f6583709f7797becb3eef7d5f254..e480573a5ff59ce2ae78793427e61b85dce7eef1:/stglibs/smux.lib/per_support.c

diff --git a/stglibs/smux.lib/per_support.c b/stglibs/smux.lib/per_support.c
new file mode 100644
index 00000000..c8344193
--- /dev/null
+++ b/stglibs/smux.lib/per_support.c
@@ -0,0 +1,318 @@
+/*
+ * Copyright (c) 2005, 2006 Lev Walkin <vlm@lionet.info>. All rights reserved.
+ * Redistribution and modifications are permitted subject to BSD license.
+ */
+#include <asn_system.h>
+#include <asn_internal.h>
+#include <per_support.h>
+
+/*
+ * Extract a small number of bits (<= 31) from the specified PER data pointer.
+ */
+int32_t
+per_get_few_bits(asn_per_data_t *pd, int nbits) {
+	size_t off;	/* Next after last bit offset */
+	uint32_t accum;
+	const uint8_t *buf;
+
+	if(nbits < 0 || pd->nboff + nbits > pd->nbits)
+		return -1;
+
+	ASN_DEBUG("[PER get %d bits from %p+%d bits]",
+		nbits, pd->buffer, pd->nboff);
+
+	/*
+	 * Normalize position indicator.
+	 */
+	if(pd->nboff >= 8) {
+		pd->buffer += (pd->nboff >> 3);
+		pd->nbits  -= (pd->nboff & ~0x07);
+		pd->nboff  &= 0x07;
+	}
+	off = (pd->nboff += nbits);
+	buf = pd->buffer;
+
+	/*
+	 * Extract specified number of bits.
+	 */
+	if(off <= 8)
+		accum = nbits ? (buf[0]) >> (8 - off) : 0;
+	else if(off <= 16)
+		accum = ((buf[0] << 8) + buf[1]) >> (16 - off);
+	else if(off <= 24)
+		accum = ((buf[0] << 16) + (buf[1] << 8) + buf[2]) >> (24 - off);
+	else if(off <= 31)
+		accum = ((buf[0] << 24) + (buf[1] << 16)
+			+ (buf[2] << 8) + (buf[3])) >> (32 - off);
+	else if(nbits <= 31) {
+		asn_per_data_t tpd = *pd;
+		/* Here are we with our 31-bits limit plus 1..7 bits offset. */
+		tpd.nboff -= nbits;
+		accum  = per_get_few_bits(&tpd, nbits - 24) << 24;
+		accum |= per_get_few_bits(&tpd, 24);
+	} else {
+		pd->nboff -= nbits;	/* Oops, revert back */
+		return -1;
+	}
+
+	return (accum & (((uint32_t)1 << nbits) - 1));
+}
+
+/*
+ * Extract a large number of bits from the specified PER data pointer.
+ */
+int
+per_get_many_bits(asn_per_data_t *pd, uint8_t *dst, int alright, int nbits) {
+	int32_t value;
+
+	if(alright && (nbits & 7)) {
+		/* Perform right alignment of a first few bits */
+		value = per_get_few_bits(pd, nbits & 0x07);
+		if(value < 0) return -1;
+		*dst++ = value;	/* value is already right-aligned */
+		nbits &= ~7;
+	}
+
+	while(nbits) {
+		if(nbits >= 24) {
+			value = per_get_few_bits(pd, 24);
+			if(value < 0) return -1;
+			*(dst++) = value >> 16;
+			*(dst++) = value >> 8;
+			*(dst++) = value;
+			nbits -= 24;
+		} else {
+			value = per_get_few_bits(pd, nbits);
+			if(value < 0) return -1;
+			if(nbits & 7) {	/* implies left alignment */
+				value <<= 8 - (nbits & 7),
+				nbits += 8 - (nbits & 7);
+				if(nbits > 24)
+					*dst++ = value >> 24;
+			}
+			if(nbits > 16)
+				*dst++ = value >> 16;
+			if(nbits > 8)
+				*dst++ = value >> 8;
+			*dst++ = value;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Get the length "n" from the stream.
+ */
+ssize_t
+uper_get_length(asn_per_data_t *pd, int ebits, int *repeat) {
+	ssize_t value;
+
+	*repeat = 0;
+
+	if(ebits >= 0) return per_get_few_bits(pd, ebits);
+
+	value = per_get_few_bits(pd, 8);
+	if(value < 0) return -1;
+	if((value & 128) == 0)	/* #10.9.3.6 */
+		return (value & 0x7F);
+	if((value & 64) == 0) {	/* #10.9.3.7 */
+		value = ((value & 63) << 8) | per_get_few_bits(pd, 8);
+		if(value < 0) return -1;
+		return value;
+	}
+	value &= 63;	/* this is "m" from X.691, #10.9.3.8 */
+	if(value < 1 || value > 4)
+		return -1;
+	*repeat = 1;
+	return (16384 * value);
+}
+
+/*
+ * Get the normally small non-negative whole number.
+ * X.691, #10.6
+ */
+ssize_t
+uper_get_nsnnwn(asn_per_data_t *pd) {
+	ssize_t value;
+
+	value = per_get_few_bits(pd, 7);
+	if(value & 64) {	/* implicit (value < 0) */
+		value &= 63;
+		value <<= 2;
+		value |= per_get_few_bits(pd, 2);
+		if(value & 128)	/* implicit (value < 0) */
+			return -1;
+		if(value == 0)
+			return 0;
+		if(value >= 3)
+			return -1;
+		value = per_get_few_bits(pd, 8 * value);
+		return value;
+	}
+
+	return value;
+}
+
+/*
+ * Put the normally small non-negative whole number.
+ * X.691, #10.6
+ */
+int
+uper_put_nsnnwn(asn_per_outp_t *po, int n) {
+	int bytes;
+
+	if(n <= 63) {
+		if(n < 0) return -1;
+		return per_put_few_bits(po, n, 7);
+	}
+	if(n < 256)
+		bytes = 1;
+	else if(n < 65536)
+		bytes = 2;
+	else if(n < 256 * 65536)
+		bytes = 3;
+	else
+		return -1;	/* This is not a "normally small" value */
+	if(per_put_few_bits(po, bytes, 8))
+		return -1;
+
+	return per_put_few_bits(po, n, 8 * bytes);
+}
+
+
+/*
+ * Put a small number of bits (<= 31).
+ */
+int
+per_put_few_bits(asn_per_outp_t *po, uint32_t bits, int obits) {
+	size_t off;	/* Next after last bit offset */
+	size_t omsk;	/* Existing last byte meaningful bits mask */
+	uint8_t *buf;
+
+	if(obits <= 0 || obits >= 32) return obits ? -1 : 0;
+
+	ASN_DEBUG("[PER put %d bits to %p+%d bits]",
+			obits, po->buffer, po->nboff);
+
+	/*
+	 * Normalize position indicator.
+	 */
+	if(po->nboff >= 8) {
+		po->buffer += (po->nboff >> 3);
+		po->nbits  -= (po->nboff & ~0x07);
+		po->nboff  &= 0x07;
+	}
+
+	/*
+	 * Flush whole-bytes output, if necessary.
+	 */
+	if(po->nboff + obits > po->nbits) {
+		int complete_bytes = (po->buffer - po->tmpspace);
+		if(po->outper(po->buffer, complete_bytes, po->op_key) < 0)
+			return -1;
+		if(po->nboff)
+			po->tmpspace[0] = po->buffer[0];
+		po->buffer = po->tmpspace;
+		po->nbits = 8 * sizeof(po->tmpspace);
+		po->flushed_bytes += complete_bytes;
+	}
+
+	/*
+	 * Now, due to sizeof(tmpspace), we are guaranteed large enough space.
+	 */
+	buf = po->buffer;
+	omsk = ~((1 << (8 - po->nboff)) - 1);
+	off = (po->nboff += obits);
+
+	/* Clear data of debris before meaningful bits */
+	bits &= (((uint32_t)1 << obits) - 1);
+
+	ASN_DEBUG("[PER out %d %u/%x (t=%d,o=%d) %x&%x=%x]", obits, bits, bits,
+		po->nboff - obits, off, buf[0], omsk&0xff, buf[0] & omsk);
+
+	if(off <= 8)	/* Completely within 1 byte */
+		bits <<= (8 - off),
+		buf[0] = (buf[0] & omsk) | bits;
+	else if(off <= 16)
+		bits <<= (16 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 8),
+		buf[1] = bits;
+	else if(off <= 24)
+		bits <<= (24 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 16),
+		buf[1] = bits >> 8,
+		buf[2] = bits;
+	else if(off <= 31)
+		bits <<= (32 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 24),
+		buf[1] = bits >> 16,
+		buf[2] = bits >> 8,
+		buf[3] = bits;
+	else {
+		ASN_DEBUG("->[PER out split %d]", obits);
+		per_put_few_bits(po, bits >> 8, 24);
+		per_put_few_bits(po, bits, obits - 24);
+		ASN_DEBUG("<-[PER out split %d]", obits);
+	}
+
+	ASN_DEBUG("[PER out %u/%x => %02x buf+%d]",
+		bits, bits, buf[0], po->buffer - po->tmpspace);
+
+	return 0;
+}
+
+
+/*
+ * Output a large number of bits.
+ */
+int
+per_put_many_bits(asn_per_outp_t *po, const uint8_t *src, int nbits) {
+
+	while(nbits) {
+		uint32_t value;
+
+		if(nbits >= 24) {
+			value = (src[0] << 16) | (src[1] << 8) | src[2];
+			src += 3;
+			nbits -= 24;
+			if(per_put_few_bits(po, value, 24))
+				return -1;
+		} else {
+			value = src[0];
+			if(nbits > 8)
+				value = (value << 8) | src[1];
+			if(nbits > 16)
+				value = (value << 8) | src[2];
+			if(nbits & 0x07)
+				value >>= (8 - (nbits & 0x07));
+			if(per_put_few_bits(po, value, nbits))
+				return -1;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+/*
+ * Put the length "n" (or part of it) into the stream.
+ */
+ssize_t
+uper_put_length(asn_per_outp_t *po, size_t length) {
+
+	if(length <= 127)	/* #10.9.3.6 */
+		return per_put_few_bits(po, length, 8)
+			? -1 : (ssize_t)length;
+	else if(length < 16384)	/* #10.9.3.7 */
+		return per_put_few_bits(po, length|0x8000, 16)
+			? -1 : (ssize_t)length;
+
+	length >>= 14;
+	if(length > 4) length = 4;
+
+	return per_put_few_bits(po, 0xC0 | length, 8)
+			? -1 : (ssize_t)(length << 14);
+}
+