extern int x1f4_step_routine (void *subtext);
x1f4_slip_routine function executes the next instruction of the
program for which the
subtext step by step execution context was
See Imperative Program Execution.
See Step By Step Imperative Program Execution Example.
The function returns
X1f4_EX_LEAD_CALL if a function to be executed
outside the interpreter control is next to be called,
if the program execution completed,
0 for otherwise successful
execution, a non zero value for failure.
See Execution Conditions.
X1f4_EX_LEAD_CALL returns mark partial instruction execution. No
temporaries are to be disposed of until instruction execution completes.