User guide

50 CHAPTER 3. THE LIBRARY

P2 L2 fn sz c P1 L1 0 c

K9G 24 cowait(c)

LP3

J -7 } REPEAT

K6 fn( ... )

LP5 {PC

The new coroutine

coroutine chain

fn sz c

stack frame

createco

stack frame

changeco

colist

currco

SP5 c := ...

Figure 3.3: The state just after changeco(0,c) in createco

devid := createdev(dcb) CIN:n, POS:y, NAT:n

This Cintpos fun ct i on creates a device using the ﬁrst available slot in devtab. The

device control block dcb must have already been initialised and li nked to its devi c e

driver. If su cc e ssf ul it returns a negative value identifying the device. On fail ur e it

returns zero with result2 set to 104 if the devtab is full, or to 106 if devi ce initialisation

failed.

res := createtask(seglist, stsize, pri) CIN:n, POS:y, NAT:n

This Cintpos function creates a task using the ﬁrst free slot in the task table. It

allocates space for the new task control block (TCB) and a copy of the speciﬁed segment

list, and initialises them both. It inserts the new TCB in priority chain of tasks and

returns the id of the newly created task if successful. It is left in DEAD state with no

stack or global vector and no packets on its work queue. If there is an error, it returns

zero with result2 set to 102 if there is already a task with priority pri, or to 103 if

there is insuﬃcient memor y or to 105 if the task table is full. A segment list is a s mal l

vector whose zeroth element holds it upperbound and whose other element hole lists

of sections of code typically loaded by loadseg.

datstamp(datv) CIN:y, POS:y, NAT:y

This sets datv!0 to the number of days since 1 January 1970, and datv!1 to the

number of milli-seconds since midnight, and for compatability with the older version

of datstamp datv!2=-1 indicating the new date and time format is being used.

dat

to string(datv, v) CIN:y, POS:y, NAT:y