User guide

3.3. GLOBAL FUNCTIONS 45

deﬁned i n the standard re si de nt library. Most of these are deﬁned in BCPL in the ﬁles:

sysb/klib.b, sysb/blib.b and sysb/dlib.b, one library (cin/syscin/syslib) is in

hand written Cintcode since it contains instructions that cannot be generated by the

BCPL compiler. The functions deﬁned in syslib are sys, changeco and muldiv.

The standard library functions are described in alphabetical order.

abort(code) CIN:y, POS:y, NAT:n

This causes an exit from the current invocation of the interpre te r , returning code

as the error code. If code is zero execution exits from the Cintcode system. If code

is -1 execution resumes using the faster version of the interpreter (fasterp). If code

is -2 the entire Cintcode memory is written to ﬁle DUMP.mem is a compacted form for

processing by CLI commands such as dumpsys or dumpdebug. If code is positive, under

normal conditions, the interactive debugger is entered.

res := appendstream(scb) CIN:y, POS:y, NAT:y

This function sets the position of stream scb to the end so that anything written

to the stream will be appended. The result is FALSE if scb is not an inout stream or

cannot be positioned for other reasons. It returns TRUE oth er wi se .

ch := binrdch() CIN:y, POS:y, NAT:y

This call behaves like rdch() but does not skip over carriage return (’*c’) char-

acters.

ch := binwrch(ch) CIN:y, POS:y, NAT:y

This call behaves like wrch(ch) but does treat ch as a special character and so

does not call deplete at the end of lines and does not inser t carriage return (’*c’)

characters.

res := callco(cptr, arg) CIN:y, POS:y, NAT:y

This call suspends the current coroutine and transfers control to the corou-

tine point e d t o by cptr. It does this by resuming execution of the functi on that

caused its suspension, which then immediately returns yi e l di ng arg as result. When

callco(cptr,arg) next receives control it yiel ds the result it is given. The deﬁnition of

callco is i n blib.b and is as follows.

LET callco(cptr, a) = VALOF

{ IF cptr!co_parent DO abort(110)

cptr!co_parent := currco

RESULTIS changeco(a, cptr)

}

res := callseg(name, a1, a2, a3, a4) CIN:y, POS:y, NAT:y

This function loads the compiled program f rom the ﬁle name, initialises its global

variables and calls start with the four arguments a1,...,a4. It returns the result of

this call, after unloading the program.