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[DCCP]: 48-bit sequence number arithmetic 

This patch
 * organizes the sequence arithmetic functions into one corner of dccp.h
 * performs a small modification of dccp_set_seqno to make it more widely reusable
   (now it is safe to use any number, since it performs modulo-2^48 assignment)
 * adds functions and generic macros for 48-bit sequence arithmetic:
 	--48 bit complement
 	--modulo-48 addition and modulo-48 subtraction
	--dccp_inc_seqno now a special case of add48
Constants renamed following a suggestion by Arnaldo.

Signed-off-by: Gerrit Renker <gerrit@erg.abdn.ac.uk>
Acked-by: Ian McDonald <ian.mcdonald@jandi.co.nz>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Gerrit Renker 2007-03-20 12:26:51 -03:00 committed by David S. Miller
parent 8b5be26831
commit 6b811d43f6
2 changed files with 28 additions and 21 deletions
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2
net/dccp/ackvec.c
View File

@ -157,7 +157,7 @@ struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority)
if (av != NULL) { if (av != NULL) {
av->dccpav_buf_head = DCCP_MAX_ACKVEC_LEN - 1; av->dccpav_buf_head = DCCP_MAX_ACKVEC_LEN - 1;
av->dccpav_buf_ackno = DCCP_MAX_SEQNO + 1; av->dccpav_buf_ackno = UINT48_MAX + 1;
av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0; av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0;
av->dccpav_time.tv_sec = 0; av->dccpav_time.tv_sec = 0;
av->dccpav_time.tv_usec = 0; av->dccpav_time.tv_usec = 0;

47
net/dccp/dccp.h
View File

@ -92,6 +92,32 @@ extern int sysctl_dccp_feat_send_ack_vector;
extern int sysctl_dccp_feat_send_ndp_count; extern int sysctl_dccp_feat_send_ndp_count;
extern int sysctl_dccp_tx_qlen; extern int sysctl_dccp_tx_qlen;
/*
* 48-bit sequence number arithmetic (signed and unsigned)
*/
#define INT48_MIN 0x800000000000LL /* 2^47 */
#define UINT48_MAX 0xFFFFFFFFFFFFLL /* 2^48 - 1 */
#define COMPLEMENT48(x) (0x1000000000000LL - (x)) /* 2^48 - x */
#define TO_SIGNED48(x) (((x) < INT48_MIN)? (x) : -COMPLEMENT48( (x)))
#define TO_UNSIGNED48(x) (((x) >= 0)? (x) : COMPLEMENT48(-(x)))
#define ADD48(a, b) (((a) + (b)) & UINT48_MAX)
#define SUB48(a, b) ADD48((a), COMPLEMENT48(b))
static inline void dccp_set_seqno(u64 *seqno, u64 value)
{
*seqno = value & UINT48_MAX;
}
static inline void dccp_inc_seqno(u64 *seqno)
{
*seqno = ADD48(*seqno, 1);
}
static inline u64 dccp_delta_seqno(u64 seqno1, u64 seqno2)
{
return ((seqno2 << 16) - (seqno1 << 16)) >> 16;
}
/* is seq1 < seq2 ? */ /* is seq1 < seq2 ? */
static inline int before48(const u64 seq1, const u64 seq2) static inline int before48(const u64 seq1, const u64 seq2)
{ {
@ -313,26 +339,7 @@ static inline int dccp_packet_without_ack(const struct sk_buff *skb)
return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST; return type == DCCP_PKT_DATA || type == DCCP_PKT_REQUEST;
} }
#define DCCP_MAX_SEQNO ((((u64)1) << 48) - 1) #define DCCP_PKT_WITHOUT_ACK_SEQ (UINT48_MAX << 2)
#define DCCP_PKT_WITHOUT_ACK_SEQ (DCCP_MAX_SEQNO << 2)
static inline void dccp_set_seqno(u64 *seqno, u64 value)
{
if (value > DCCP_MAX_SEQNO)
value -= DCCP_MAX_SEQNO + 1;
*seqno = value;
}
static inline u64 dccp_delta_seqno(u64 seqno1, u64 seqno2)
{
return ((seqno2 << 16) - (seqno1 << 16)) >> 16;
}
static inline void dccp_inc_seqno(u64 *seqno)
{
if (++*seqno > DCCP_MAX_SEQNO)
*seqno = 0;
}
static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss) static inline void dccp_hdr_set_seq(struct dccp_hdr *dh, const u64 gss)
{ {