If “N” is a node key and 0 ≤ n ≤ 15 then
N(NODE__FETCH{=0}+n;==>;K) copies the key in slot n of node N to K.

N(NODE__SWAP{=16}+n;K==>;L) copies K to slot n of N and returns in L the old contents of slot n.

{arcane}If either (N is the domain root of the returnee and n is 14 or 15 {(p1,worsejump48)}) or N is the returnee’s general registers node {(p1,worsejump49)}, the jumper will trap.

Fx is the first slot number to be stored into, and lx is the last slot number to be stored into. If these are not both < 16, c=1 and the node is unchanged. Slot 0 is considered to follow slot 15.

“Data” consists of a sequence of 16-byte values, one for each slot to be changed, in order. Each slot will receive a data key with the corresponding value mod 256¹¹. If any value is not less than 256¹¹ {11 bytes} then c=2. Otherwise c=0.

{arcane}Fine print: the situations of (p1,worsejump48) and (p1,worsejump49) are possible.

If K is a node key, fetch key, sense key, segment key or meter key to N’s node, then N(NODE__COMPARE{=38};K==>c;) returns 0 in c, and 1 otherwise.

{ni}This call should return the data byte of K as well!

N(NODE__DATA_BYTE{=40};==>c;) returns the databyte of N in c.

N(kt;==>c;) returns 3 in c.

These values without the underscores are in the macro NODEDEFS in the library DOMAIN. NODE__FETCH=0, NODE__SWAP=16,
NODE__MAKE_FETCH_KEY=32, NODE__MAKE_SEGMENT_KEY=33, NODE__MAKE_METER_KEY=34, NODE__MAKE_NODE_KEY=35, NODE__COMPARE=38, NODE__CLEAR=39, NODE__DATA_BYTE=40, NODE__WRITE_DATA=45.

Design Note:

The following would provide an efficient semephore function:

If slot n of a NODE holds a resume key EX then NODE(64+n;=>0;) forks EX thus: EX(0;). Otherwise the caller’s return key is placed in slot n and the caller remains waiting. See (jmeet) for a similar available function.