X-Git-Url: https://git.stg.codes/stg.git/blobdiff_plain/b27841d687ec9e84983340b5581376dfb24010ea..b2b89723a2427bba8290bd6967a1ab39cbb630be:/libs/smux/asn_bit_data.c

diff --git a/libs/smux/asn_bit_data.c b/libs/smux/asn_bit_data.c
new file mode 100644
index 00000000..fe4b89ba
--- /dev/null
+++ b/libs/smux/asn_bit_data.c
@@ -0,0 +1,333 @@
+/*
+ * Copyright (c) 2005-2017 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 <asn_bit_data.h>
+
+/*
+ * Create a contiguous non-refillable bit data structure.
+ * Can be freed by FREEMEM().
+ */
+asn_bit_data_t *
+asn_bit_data_new_contiguous(const void *data, size_t size_bits) {
+    size_t size_bytes = (size_bits + 7) / 8;
+    asn_bit_data_t *pd;
+    uint8_t *bytes;
+
+    /* Get the extensions map */
+    pd = CALLOC(1, sizeof(*pd) + size_bytes + 1);
+    if(!pd) {
+        return NULL;
+    }
+    bytes = (void *)(((char *)pd) + sizeof(*pd));
+    memcpy(bytes, data, size_bytes);
+    bytes[size_bytes] = 0;
+    pd->buffer = bytes;
+    pd->nboff = 0;
+    pd->nbits = size_bits;
+
+    return pd;
+}
+
+
+char *
+asn_bit_data_string(asn_bit_data_t *pd) {
+	static char buf[2][32];
+	static int n;
+	n = (n+1) % 2;
+    snprintf(buf[n], sizeof(buf[n]),
+             "{m=%" ASN_PRI_SIZE " span %" ASN_PRI_SIZE "[%" ASN_PRI_SIZE
+             "..%" ASN_PRI_SIZE "] (%" ASN_PRI_SIZE ")}",
+             pd->moved, ((uintptr_t)(pd->buffer) & 0xf), pd->nboff, pd->nbits,
+             pd->nbits - pd->nboff);
+    return buf[n];
+}
+
+void
+asn_get_undo(asn_bit_data_t *pd, int nbits) {
+	if((ssize_t)pd->nboff < nbits) {
+		assert((ssize_t)pd->nboff < nbits);
+	} else {
+		pd->nboff -= nbits;
+		pd->moved -= nbits;
+	}
+}
+
+/*
+ * Extract a small number of bits (<= 31) from the specified PER data pointer.
+ */
+int32_t
+asn_get_few_bits(asn_bit_data_t *pd, int nbits) {
+	size_t off;	/* Next after last bit offset */
+	ssize_t nleft;	/* Number of bits left in this stream */
+	uint32_t accum;
+	const uint8_t *buf;
+
+	if(nbits < 0)
+		return -1;
+
+	nleft = pd->nbits - pd->nboff;
+	if(nbits > nleft) {
+		int32_t tailv, vhead;
+		if(!pd->refill || nbits > 31) return -1;
+		/* Accumulate unused bytes before refill */
+		ASN_DEBUG("Obtain the rest %d bits (want %d)",
+			(int)nleft, (int)nbits);
+		tailv = asn_get_few_bits(pd, nleft);
+		if(tailv < 0) return -1;
+		/* Refill (replace pd contents with new data) */
+		if(pd->refill(pd))
+			return -1;
+		nbits -= nleft;
+		vhead = asn_get_few_bits(pd, nbits);
+		/* Combine the rest of previous pd with the head of new one */
+		tailv = (tailv << nbits) | vhead;  /* Could == -1 */
+		return tailv;
+	}
+
+	/*
+	 * Normalize position indicator.
+	 */
+	if(pd->nboff >= 8) {
+		pd->buffer += (pd->nboff >> 3);
+		pd->nbits  -= (pd->nboff & ~0x07);
+		pd->nboff  &= 0x07;
+	}
+	pd->moved += nbits;
+	pd->nboff += nbits;
+	off = pd->nboff;
+	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 = (((uint32_t)buf[0] << 24) + (buf[1] << 16)
+			+ (buf[2] << 8) + (buf[3])) >> (32 - off);
+	else if(nbits <= 31) {
+		asn_bit_data_t tpd = *pd;
+		/* Here are we with our 31-bits limit plus 1..7 bits offset. */
+		asn_get_undo(&tpd, nbits);
+		/* The number of available bits in the stream allow
+		 * for the following operations to take place without
+		 * invoking the ->refill() function */
+		accum  = asn_get_few_bits(&tpd, nbits - 24) << 24;
+		accum |= asn_get_few_bits(&tpd, 24);
+	} else {
+		asn_get_undo(pd, nbits);
+		return -1;
+	}
+
+	accum &= (((uint32_t)1 << nbits) - 1);
+
+	ASN_DEBUG("  [PER got %2d<=%2d bits => span %d %+ld[%d..%d]:%02x (%d) => 0x%x]",
+		(int)nbits, (int)nleft,
+		(int)pd->moved,
+		(((long)pd->buffer) & 0xf),
+		(int)pd->nboff, (int)pd->nbits,
+		((pd->buffer != NULL)?pd->buffer[0]:0),
+		(int)(pd->nbits - pd->nboff),
+		(int)accum);
+
+	return accum;
+}
+
+/*
+ * Extract a large number of bits from the specified PER data pointer.
+ */
+int
+asn_get_many_bits(asn_bit_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 = asn_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 = asn_get_few_bits(pd, 24);
+			if(value < 0) return -1;
+			*(dst++) = value >> 16;
+			*(dst++) = value >> 8;
+			*(dst++) = value;
+			nbits -= 24;
+		} else {
+			value = asn_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;
+}
+
+/*
+ * Put a small number of bits (<= 31).
+ */
+int
+asn_put_few_bits(asn_bit_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 %x to %p+%d bits]",
+			obits, (int)bits, (void *)po->buffer, (int)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) {
+		size_t complete_bytes;
+		if(!po->buffer) po->buffer = po->tmpspace;
+		complete_bytes = (po->buffer - po->tmpspace);
+		ASN_DEBUG("[PER output %ld complete + %ld]",
+			(long)complete_bytes, (long)po->flushed_bytes);
+		if(po->output(po->tmpspace, 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,
+		(int)bits, (int)bits,
+		(int)po->nboff, (int)off,
+		buf[0], (int)(omsk&0xff),
+		(int)(buf[0] & omsk));
+
+	if(off <= 8)	/* Completely within 1 byte */
+		po->nboff = off,
+		bits <<= (8 - off),
+		buf[0] = (buf[0] & omsk) | bits;
+	else if(off <= 16)
+		po->nboff = off,
+		bits <<= (16 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 8),
+		buf[1] = bits;
+	else if(off <= 24)
+		po->nboff = off,
+		bits <<= (24 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 16),
+		buf[1] = bits >> 8,
+		buf[2] = bits;
+	else if(off <= 31)
+		po->nboff = off,
+		bits <<= (32 - off),
+		buf[0] = (buf[0] & omsk) | (bits >> 24),
+		buf[1] = bits >> 16,
+		buf[2] = bits >> 8,
+		buf[3] = bits;
+	else {
+		if(asn_put_few_bits(po, bits >> (obits - 24), 24)) return -1;
+		if(asn_put_few_bits(po, bits, obits - 24)) return -1;
+	}
+
+	ASN_DEBUG("[PER out %u/%x => %02x buf+%ld]",
+		(int)bits, (int)bits, buf[0],
+		(long)(po->buffer - po->tmpspace));
+
+	return 0;
+}
+
+
+/*
+ * Output a large number of bits.
+ */
+int
+asn_put_many_bits(asn_bit_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(asn_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(asn_put_few_bits(po, value, nbits))
+				return -1;
+			break;
+		}
+	}
+
+	return 0;
+}
+
+
+int
+asn_put_aligned_flush(asn_bit_outp_t *po) {
+    uint32_t unused_bits = (0x7 & (8 - (po->nboff & 0x07)));
+    size_t complete_bytes =
+        (po->buffer ? po->buffer - po->tmpspace : 0) + ((po->nboff + 7) >> 3);
+
+    if(unused_bits) {
+        po->buffer[po->nboff >> 3] &= ~0u << unused_bits;
+    }
+
+    if(po->output(po->tmpspace, complete_bytes, po->op_key) < 0) {
+        return -1;
+    } else {
+        po->buffer = po->tmpspace;
+        po->nboff = 0;
+        po->nbits = 8 * sizeof(po->tmpspace);
+        po->flushed_bytes += complete_bytes;
+        return 0;
+    }
+}
+