perm filename SAIL.DOC[DOC,AIL]1 blob
sn#075606 filedate 1973-12-08 generic text, type T, neo UTF8
SAIL Addendum 1 TABLE OF CONTENTS
T A B L E O F C O N T E N T S
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _
SECTION PAGE
1 INTRODUCTION
2 NUMERICAL ROUTINES
1 OVERFLOW 3
2 ENTRY POINTS 4
3 PROCESS: NEW FEATURES
1 SPROUT APPLY 5
2 SPROUT_DEFAULTS 5
3 SUSPEND 7
4 FAIL AND SUCCEED 7
4 ERROR HANDLING
1 ERROR MODES 8
2 USER ERROR PROCEDURES 8
5 INEXHAUSTIBLE STRING SPACE
6 MISCELLANEOUS NEW FEATURES
1 NEW MTAPE OPTION 12
2 INITIALIZATION PHASES 12
3 CHNCDB 13
4 ARRCLR 13
5 SETPL 13
6 EVALREDEFINE 14
7 CVPS 14
8 EXPRESSIONS IN REQUIRES 14
9 RELEASE 14
SAIL Addendum 1 INTRODUCTION
SECTION 1
_______ _
INTRODUCTION
____________
The following short manual describes the changes that have happened
to SAIL since the publishing of the Manual in July 1973. It
accurately reflects the state of SAIL, version 7, which was put up on
December 4, 1973. The reader should be warned that many of these new
features were designed for veteran SAIL hackers.
The reader may also want to refer to the following documents, which
are usually kept updated.
MACLIE.WRU[DOC,AIL] A summary of commonly made errors when using
macros and what to do about them.
TUTOR.DOC[DOC,AIL] In introduction to LEAP.
LEAP.WRU[DOC,AIL] A detailed description of the runtime environment
of LEAP for the hardy few who want to interface
to LEAP in assembly language.
SAIL.DOC[AIM,DOC] The July '73 manual (AIM-204) in LPT form.
Warning: this version is the Stanford character
set. It is also almost 300 pages long. You can
get a 120 page version, set in two columns of
nice type from the National Technical Information
Service, Springfield, Virginia 22151.
LIES[DOC,AIL] This file contains the know mistakes in the
Manual. Soon it will also contain the known
mistakes in this document.
1
SAIL Addendum 1 NUMERICAL ROUTINES
SECTION 2
_______ _
NUMERICAL ROUTINES
_________ ________
A collection of numerical routines has been added to SAIL. These are
pre-declared in the compiler, and are loaded from the standard SAIL
library. The functions are quite standard; following are the
equivalent definitions:
1. The standard trigonometric functions. ASIN, ACOS, ATAN and ATAN2
return results in radians. The ATAN2 call takes arc-tangent of
the quotient of its arguments; in this way, it correctly
preserves sign information.
REAL PROCEDURE SIN (REAL RADIANS);
REAL PROCEDURE COS (REAL RADIANS);
REAL PROCEDURE SIND (REAL DEGREES);
REAL PROCEDURE COSD (REAL DEGREES);
REAL PROCEDURE ASIN (REAL ARGUMENT);
REAL PROCEDURE ACOS (REAL ARGUMENT);
REAL PROCEDURE ATAN (REAL ARGUMENT);
REAL PROCEDURE ATAN2 (REAL NUMERATOR,DENOMINATOR);
2. The hyperbolic trigonometric functions.
REAL PROCEDURE SINH (REAL ARGUMENT);
REAL PROCEDURE COSH (REAL ARGUMENT);
REAL PROCEDURE TANH (REAL ARGUMENT);
3. The square-root function:
REAL PROCEDURE SQRT (REAL ARGUMENT);
4. A pseudo-random number generator. The argument specifies a new
value for the seed (If the argument is 0, the old seed value is
used. Thus to get differing random numbers, this argument should
be zero.) Results are normalized to lie in the range [0,1].
REAL PROCEDURE RAN (INTEGER SEED);
2
SAIL Addendum 1 NUMERICAL ROUTINES
5. Logarithm and exponentiation functions. These functions are the
same ones used by the SAIL exponentiation operator. The base is
e (2.71828182845904). The logarithm to the base 10 of e is
.4342944819.
REAL PROCEDURE LOG (REAL ARGUMENT);
REAL PROCEDURE EXP (REAL ARGUMENT);
These functions may occasionally be asked to compute numbers that lie
outside the range of legal floating-point numbers on the PDP-10. In
these cases, the routines issue sprightly error messages that are
continuable.
2.1 - OVERFLOW
________
In order to better perform their tasks, these routines enable the
system interrupt facility for floating-point overflow and underflow
errors. If an underflow is detected, the results are set to 0 (a
feat not done by the PDP-10 hardware, alas). Be aware that such
underflow fixups will be done to every underflow that occurs in your
program.
If you would like to be informed of any numerical exceptions, you can
call the runtime:
TRIGINI ( LOCATION(simple-procedure-name) );
Every floating-point exception that is not expected by the interrupt
handler (the numerical routines use a special convention to indicate
that arithmetic exception was expected) will cause the specified
simple procedure to be called. This procedure may look around the
world as described in the Manual for 'export' interrupt handlers,
page 79. If no TRIGINI call is done, the interrupt routine will
simply dismiss unexpected floating-point interrupts.
3
SAIL Addendum 1 NUMERICAL ROUTINES
2.2 - ENTRY POINTS
_____ ______
In order to avoid confusion (by the loader) with older trig packages,
the entry points of the SAIL arithmetic routines all have a "$"
appended to the end. Thus, SIN has the entry point SIN$, etc.
WARNING: If a program plans to use the SAIL intrinsic numerical
routines, it should NOT include external declarations to them, since
this will probably cause the FORTRAN library routines to be loaded.
3
4
SAIL Addendum 1 PROCESS: NEW FEATURES
SECTION 3
_______ _
PROCESS: NEW FEATURES
________ ___ ________
3.1 - SPROUT APPLY
______ _____
The <procedure call> in a SPROUT statement may be an APPLY construct.
In this case SPROUT will do the "right" thing about setting up the
static link for the APPLY. That is, "up-level" references by the
process will be made to the same variable instances that would be
used if the APPLY did not occur in a SPROUT statement. (See page 77
of the manual.)
However, there is a glitch. The sprout mechanism is not yet smart
enough to find out the block of the declaration of the procedure used
to define the procedure item. It would be nice if it did, since then
it could warn the user when that block was exited and yet the process
was still alive, and thus potentially able to refer to deallocated
arrays and etc. What the sprout does instead is assume the procedure
was declared in the outer block. This may be fixed eventually, but
in the meantime some extra care should be taken when using apply
in sprouts to avoid exiting a block with dependents.
Similarly, be warned that the "DEPENDENTS (<blockid>)" construct
may not give the "right" result for sprout applies. Page 68 of
the Manual contains the description of this protection mechanism for
non-APPLY Sprouts.
3.2 - SPROUT_DEFAULTS
_______________
SAIL now provides a mechanism by which the user may specify the
"default" options to be used when individual procedures are sprouted.
5
SAIL Addendum 1 PROCESS: NEW FEATURES
Syntax:
PROCEDURE <procid> ...
BEGIN
<some declarations>;
SPROUT_DEFAULTS <integer constant>;
<perhaps some more declarations>;
:
:
<statements>
:
END;
In other words, SPROUT_DEFAULTS is a declaration.
Semantics:
If one of the "allocation" fields of the options word passed to the
SPROUT routine -- i.e. QUANTUM,STRINGSTACK,PSTACK, or PRIORITY -- is
zero, then SPROUT will look at the corresponding field of the
specified <integer constant> for the procedure being sprouted. If the
field is non-zero, then that value will be used; otherwise the
current "system" default will be used.
NOTE: SPROUT_DEFAULTS only applies to "allocations", i.e. the
process status control bits (e.g. SUSPME) are not affected.
Example:
RECURSIVE PROCEDURE FOO;
BEGIN
SPROUT_DEFAULTS STRINGSTACK(10);
INTEGER XXX;
:
:
END;
:
SPROUT(P1,FOO,STRINGSTACK(3));
SPROUT(P2,FOO);
COMMENT P1 will have a string stack of 3*32 words.
P2 will have a string stack of 10*32 words;
6
SAIL Addendum 1 PROCESS: NEW FEATURES
3.3 - SUSPEND
_______
SUSPEND now behaves like RESUME in that it returns an item.
itm ← SUSPEND(<process item>)
Frequently, one is suspending some other process than the one that is
executing the SUSPEND statement. In this case, the item returned is
ANY. However, in cases like:
X ← SUSPEND(MYPROC);
where the process suspends itself, it might happen that this process
is made running by a RESUME from another process. If so, then X
receives the <return_item> that was an argument to the RESUME.
3.4 - FAIL AND SUCCEED
____ ___ _______
FAIL and SUCCEED now behave like RESUME and SUSPEND in that they also
return an item. The item returned is ANY unless the Matching
Procedure containing the FAIL or SUCCEED was (1) sprouted as a
process, and (2) made running by a RESUME construct. In the latter
case, the item returned is the <return_item> that was an argument to
the RESUME. [Note that the only case in which a Matching Procedure
can be reactivated at a FAIL is by being RESUMEd.]
7
SAIL Addendum 1 ERROR HANDLING
SECTION 4
_______ _
ERROR HANDLING
_____ ________
4.1 - ERROR MODES
_____ _____
SAIL's error handler has at long last been modified to do what is
claimed it will do in Section 20 of the manual (pgs 95 - 97), and in
the description of USERERR (pg 42). In brief, it allows one to have
error messages automatically sent to a "log" file while one is
compiling, and to use USERERR as a trace statement.
The description given in the manual differs from reality in two ways:
"Keep" mode has not been implemented (the error handler will flush
all type-ahead except a <lf>); all of the other modes ("Quiet",
"Logging", and "Numbers") are implemented ONLY IN THE COMPILER.
However, one can get the effect of error modes at runtime by using a
brand new feature called user error procedures.
4.2 - USER ERROR PROCEDURES
____ _____ __________
A user error procedure is a user procedure that is run before or
instead of the SAIL error handler everytime an error occurs at
runtime. This includes all array errors, IO errors, Leapish errors
and all USERERRs. It does not include system errors, such as Ill Mem
Ref or Ill UUO.
The procedure one uses for a user error procedure must be of the
following type:
SIMPLE INTEGER PROCEDURE proc (INTEGER loc; STRING msg, rsp);
Only the names proc, loc, msg, and rsp may vary from the example
above, except that one may declare the procedure INTERNAL if one
wishes to use it across files.
8
SAIL Addendum 1 ERROR HANDLING
Whenever the external integer _ERRP_ is loaded with LOCATION(proc),
the error handler will call proc before it does anything else. It
will set loc to the core location of the call to the error handler.
Msg will be the message that it would have printed. Rsp will be
non-NULL only if the error was from a USERERR which had response
string argument. Proc can do anything that a simple procedure can
do. When it exits, it should return an integer which tells the
error handler if it should do anything more. If the integer is 0,
the error handler will (1) print the message, (2) print the
location, and (3) query the tty and dispatch on the response
character (i.e ask for a <cr>, <lf>, etc.). If the right half of the
integer is non-zero, it is taken as the ascii for a character to
dispatch upon. The left half may have two bits to control printing.
If bit 17 in the integer is on, message printing is inhibited. If
bit 16 is on, then the location printing is inhibited. For example,
"X"+(1 LSH 18) will cause the location to be printed and the program
exited. "C"+(3 LSH 18) will cause the error handler to continue
without printing anything.
Note that simple procedures can not do a non-local GOTO. However,
the effect of a non-local GOTO can be achieved in a user error
procedure by loading the external integer _ERRJ_ with the LOCATION of
a label. The label should be a on a call to a non-simple procedure
which does the desired GOTO. The error handler clears _ERRJ_ before
calling the procedure in _ERRP_. If _ERRJ_ is non-zero when the
user procedure returns, and continuing was specified, then the error
handler's exit consists of a simple transfer to that location.
WARNING! Handling errors from strange places like the string garbage
collector and the core management routines will get you into deep
trouble.
9
SAIL Addendum 1 INEXHAUSTIBLE STRING SPACE
SECTION 5
_______ _
INEXHAUSTIBLE STRING SPACE
_____________ ______ _____
The string garbage collector has been modified to expand string space
(using discontiguous blocks) whenever necessary to satisfy the demand
for places to put strings. To take advantage of this feature, one
need not change his programs.
Here are some points which might be of interest, however:
1) Although we are going to provide user control over all size
parameters eventually, currently only the initial string
space size is settable by the user, either via REQUIRE or
the ALLOC sequence, as before. The size of each string space
increment will be the same as the original size, which need not
be monstrous any more unless you know that all runs of your
program will need a monstrous string space anyhow. The
threshold (see below) for expanding will be set at 1/8 the
string space size (increment size).
2) One can, in his program, modify these values independently, if he
is willing to use the USERCON function, and to follow this
format:
USER TABLE ENTRY NAME VALUE
STINCR lh: number of chars. in increment
rh: number of words in increment + 4
STREQD lh: number of chars. in threshold
rh: number of words in threshold.
3) The threshold. After garbage collection, let us say that M-1
discontiguous string spaces are full, and the M'th has n
free characters in it (available for new strings). The garbage
collector was called because some routine wanted to create a
string R characters long, and there were not that many available
(free). After garbage collection, the new algorithm
requires that N be greater than R+LH(STREQD). If it is not,
expansion takes place (to M+1 spaces), to satisfy this
requirement. In other words, if STREQD is 1/8 the size of the
current space, that space will not be allowed to become more
10
SAIL Addendum 1 INEXHAUSTIBLE STRING SPACE
than about 7/8 full. This helps avoid frequent, nearly
useless calls on the garbage collector when space is about gone.
All but the current space are allowed to become as full as
possible, however.
4) New statistics are maintained by the garbage collector.
Soon there will be a built-in routine you can use to print
them. For now, you may look at them using USERCON, although this
document does not say what they are. In order to
activate timing of the garbage collector (slows it down), set
SGCTIME in the user table to -1.
5) Future plans. The new structure not only allows expansion of
string space, it also will allow for partial garbage
collections (no visible benefits except increased speed,
since a partial collection will be almost as effective as a
complete one, and much faster), and the ability to move
string space blocks, in order to compact memory. Push on your
local representative to get these things done.
11
SAIL Addendum 1 MISCELLANEOUS NEW FEATURES
SECTION 6
_______ _
MISCELLANEOUS NEW FEATURES
_____________ ___ ________
6.1 - NEW MTAPE OPTION
___ _____ ______
In export SAIL, MTAPE(chnl,"I") sets the 'IBM compatible' mode for a
tape drive. (It does an MTAPE chnl,101.)
6.2 - INITIALIZATION PHASES
______________ ______
User initializations are now done in successive phases, with all
initializations required for one phase being done before
initializations required for the next phase.
Syntax:
REQUIRE <procid> INITIALIZATION;
REQUIRE <procid> INITIALIZATION [<phase no>];
where <phase no> is an integer constant.
Semantics:
<phase no> specifies the number of the user initialization phase.
If it is left out, then one is used. Currently, there are three
phases, numbered 0, 1, and 2. If the demand is great enough,
additional phases may be added later. (Note for assembly language
hackers: internally, user phases are numbered '400000, '400001, etc.)
12
SAIL Addendum 1 MISCELLANEOUS NEW FEATURES
6.3 - CHNCDB
______
val←CHNCDB(channel)
This integer procedure returns a pointer to the three word block used
to open the specified channel. It is provided for the benefit of
assembly language procedures that may want to do I/O inside some fast
inner loop, but which may want to live in a SAIL core image & use the
SAIL OPEN, etc.
6.4 - ARRCLR
______
This new runtime routine clears any kind of array. That is, arthmetic
arrays get filled with zeros, string arrays with NULLs, and itemvar
arrays with ANYs. One may use ARRCLR with set and list arrays, but
the set and list space will be lost (i.e. un-garbage-collectable).
The syntax is
ARRCLR ( ARRY )
6.5 - SETPL
_____
SETPL(channel, @linnum, @pagnum, @sosnum)
This new runtime routine allows one to keep track of the string input
from CHANNEL. Whenever a '12 is encountered, LINNUM is incremented.
Whenever a '14 is encountered, PAGNUM is incremented, and LINNUM is
zeroed. Whenever an SOS line number is encountered, it is placed
into SOSNUM. When fully implemented (soon), this will work on the
INPUT, INTIN, and REALIN functions as well.
13
SAIL Addendum 1 MISCELLANEOUS NEW FEATURES
6.6 - EVALREDEFINE
____________
EVALREDEFINE bears the same relationship to REDEFINE as EVALDEFINE
does to DEFINE. See pages 47 and 50 of the Manual.
6.7 - CVPS
____
CVPS(<macro_parameter>) converts <macro_parameter> to a string and
returns the string. See about macro parameters on page 48 of the
manual.
6.8 - EXPRESSIONS IN REQUIRES
___________ __ ________
Previously, all REQUIRE constructs had to have only constants in
them. Now SAIL allows compile time expressions as well. See about
compile time expressions on page 47 of the Manual.
6.9 - RELEASE
_______
RELEASE now takes an optional second argument, the CLOSE inhibit
bits. These are described in the UUO manual (Stanford System). These
are defaulted to zero when not specified so that old programs which
did not specify them will work as before.
14