Commit 6fbd8611 authored Jan 15, 2018 by Robert Chou Committed by Anas Nashif Jan 29, 2018

net: lwm2m: fix reporting attributes with negative fraction



Fraction could be stored with negative value.
The implementation was only considering the positive value case.
Therefore, we have to modify the code to take care of the case.

To test it
======================================================================
1. launch eclipse/wakaama lwm2m server
2. launch zephyr lwm2m client and wait for registration completed
3. Issue commands from server
   * attr 0 /1/0/1 -0.1 0.1
   * disc 0 /1/0

Current output
----------------------------------------------------------------------
Client #0 /1/0 : 2.05 (COAP_205_CONTENT)
105 bytes received of type application/link-format:
</1/0>,</1/0/0>,</1/0/1>;gt=0.1;lt=0/00000,</1/0/2>,</1/0/3>,</1/0/4>,
</1/0/5>,</1/0/6>,</1/0/7>,</1/0/8>

Expected output
----------------------------------------------------------------------
Client #0 /1/0 : 2.05 (COAP_205_CONTENT)
102 bytes received of type application/link-format:
</1/0>,</1/0/0>,</1/0/1>;gt=0.1;lt=-0.1,</1/0/2>,</1/0/3>,</1/0/4>,
</1/0/5>,</1/0/6>,</1/0/7>,</1/0/8>

Signed-off-by: Robert Chou <robert.ch.chou@acer.com>

parent abd54484

subsys/net/lib/lwm2m/lwm2m_engine.c

+7 −3

Original line number	Diff line number	Diff line
		@@ -2725,13 +2725,17 @@ static int print_attr(struct net_pkt pkt, char buf, u16_t buflen,

		SYS_SLIST_FOR_EACH_CONTAINER(attr_list, attr, node) {
		/* assuming integer will have float_val.val2 set as 0 */
		used = snprintk(buf, buflen, ";%s=%d%s",

		used = snprintk(buf, buflen, ";%s=%s%d%s",
		LWM2M_ATTR_STR[attr->type],
		attr->float_val.val1 == 0 &&
		attr->float_val.val2 < 0 ? "-" : "",
		attr->float_val.val1,
		attr->float_val.val2 > 0 ? "." : "");
		attr->float_val.val2 != 0 ? "." : "");

		base = 100000;
		fraction = attr->float_val.val2;
		fraction = attr->float_val.val2 < 0 ?
		-attr->float_val.val2 : attr->float_val.val2;
		while (fraction && used < buflen && base > 0) {
		digit = fraction / base;
		buf[used++] = '0' + digit;

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