Packetbuffer Basics - Revision history

Pradiptg: /* int packetbuf_hdralloc(int size) */

2014-11-08T00:07:27Z

‎int packetbuf_hdralloc(int size)

Pradiptg: /* int packetbuf_hdralloc(int size) */

2014-11-08T00:06:56Z

‎int packetbuf_hdralloc(int size)

Pradiptg: /* int packetbuf_copyto(void to) /

2014-11-08T00:05:59Z

‎int packetbuf_copyto(void *to)

Pradiptg: /* int packetbuf_copyto(void to) /

2014-11-08T00:05:30Z

‎int packetbuf_copyto(void *to)

← Older revision		Revision as of 00:07, 8 November 2014
Line 609:		Line 609:

	hdrptr -= size;		hdrptr -= size;
−	This increases the header size. Since the end location of the header is fixed at PACKETBUF_HDR_SIZE-1, only way to assign more space is to move the beginning location.	+	This increases the header size. Since the end location of the header is fixed at PACKETBUF_HDR_SIZE-1, only way to assign more space is to move the beginning location pointer.

@@ Line 606: / Line 606: @@
 if hdrptr >= size then, there is a possibility. But if the total length of the packet after adding extra space is greater PACKETBUF_SIZE then we can allocate more space.
-if hdrptr <= size or packet total nebgth + size > PACKETBUF_SIZE, it is not possible to allocate "size" amount of extra bytes or space.
+if hdrptr <= size or packet total length + size > PACKETBUF_SIZE, it is not possible to allocate "size" amount of extra bytes or space.
   hdrptr -= size;
 This increases the header size. Since the end location of the header is fixed at PACKETBUF_HDR_SIZE-1, only way to assign more space is to move the beginning location.

@@ Line 586: / Line 586: @@
   memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr);
-The following lines copies the data from the data/payload section of the packetbuf. The destination address is '''"(uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr"'''. The reason is that '''"PACKETBUF_HDR_SIZE - hdrptr"''' bytes of header data is already copied. This gives us the next available memory location. The source address is '''(packetbufptr + bufptr)'''. '''"packetbufptr"''' points to the packet's data part beginning. If the data is external, '''"packetbufptr"''' points to the external source, otherwise packetbufptr point to '''packetbuf[PACKETBUF_HDR_SIZE]'''. '''"buflen"''' is the actual size of the data i.e the number of bytes to be copied for the packet's data part only.
+The following lines copies the data from the data/payload section of the packetbuf. The destination address is '''"(uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr"'''. The reason is that '''"PACKETBUF_HDR_SIZE - hdrptr"''' bytes of header data is already copied. This gives us the next available memory location. The source address is '''(packetbufptr + bufptr)'''. '''"packetbufptr"''' points to the packet's data part beginning. If the data is external, '''"packetbufptr"''' points to the external source, otherwise '''"packetbufptr"''' points to '''packetbuf[PACKETBUF_HDR_SIZE]'''. '''"buflen"''' is the actual size of the data i.e the number of bytes to be copied for the packet's data part only.
   memcpy((uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr, packetbufptr + bufptr, buflen);

@@ Line 586: / Line 586: @@
   memcpy(to, packetbuf + hdrptr, PACKETBUF_HDR_SIZE - hdrptr);
-The following lines copies the data from the data/payload section of the packetbuf. The destination address is '''"(uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr"'''. The reason is that '''"PACKETBUF_HDR_SIZE - hdrptr"''' bytes of header data is already copied. This gives us the next available memory location. The source address is '''(packetbufptr + bufptr)'''. packetbufptr points to the packet's data part beginning. If the data is external, '''"packetbufptr"''' points to the external source, otherwise packetbufptr point to '''packetbuf[PACKETBUF_HDR_SIZE]'''. '''"buflen"''' is the actual size of the data i.e the number of bytes to be copied for the packet's data part only.
+The following lines copies the data from the data/payload section of the packetbuf. The destination address is '''"(uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr"'''. The reason is that '''"PACKETBUF_HDR_SIZE - hdrptr"''' bytes of header data is already copied. This gives us the next available memory location. The source address is '''(packetbufptr + bufptr)'''. '''"packetbufptr"''' points to the packet's data part beginning. If the data is external, '''"packetbufptr"''' points to the external source, otherwise packetbufptr point to '''packetbuf[PACKETBUF_HDR_SIZE]'''. '''"buflen"''' is the actual size of the data i.e the number of bytes to be copied for the packet's data part only.
   memcpy((uint8_t *)to + PACKETBUF_HDR_SIZE - hdrptr, packetbufptr + bufptr, buflen);

Packetbuffer Basics - Revision history

Pradiptg: /* int packetbuf_hdralloc(int size) */

Pradiptg: /* int packetbuf_hdralloc(int size) */

Pradiptg: /* int packetbuf_copyto(void *to) */

Pradiptg: /* int packetbuf_copyto(void *to) */

Pradiptg: /* int packetbuf_copyto(void to) /

Pradiptg: /* int packetbuf_copyto(void to) /