From david@imagine1.com Sat Oct 26 04:55:35 1996 Received: from kitsune.swcp.com (kitsune.swcp.com [198.59.115.2]) by dkuug.dk (8.6.12/8.6.12) with ESMTP id EAA01982 for ; Sat, 26 Oct 1996 04:55:31 +0100 Received: from ppp117.swcp.com (ppp117.swcp.com [204.134.0.227]) by kitsune.swcp.com (8.6.9/8.6.9) with SMTP id VAA23832 for ; Fri, 25 Oct 1996 21:55:17 -0600 Date: Fri, 25 Oct 1996 21:55:17 -0600 Message-Id: <199610260355.VAA23832@kitsune.swcp.com> X-Sender: evt@swcp.com (Unverified) Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="=====================_846301917==_" To: sc22wg5 From: david@imagine1.com (David Epstein) Subject: N1192r1 X-Mailer: X-Attachments: C:\DE\WG5\COCO\WG5COCO3.TXT; --=====================_846301917==_ Content-Type: text/plain; charset="us-ascii" Mallory, Please give this an X3J3 paper number. I will bring formatted printouts to LasVegas. Thanks, David ------------------------------- --=====================_846301917==_ Content-Type: text/plain; charset="us-ascii" To: X3J3 From: David Epstein Subject: N1192r1 based on ballot comments Below is a revision of N1192 based on the comments collected during the recent SC22WG5 informal ballot. David ------------------------ CONDITIONAL COMPILATION IN FORTRAN ISO/IEC 1539-3 : 1996 {Auxiliary to ISO/IEC 1539 : 1996 "Programming Language Fortran"} CONTENTS 1. Introduction 2. Rationale 3. General 1. Scope 2. Normative References 4. The Conditional Compilation Language Definition Annex CCA : Examples 1. INTRODUCTION ---------------------------------------------------- This part of ISO/IEC 1539 has been prepared by ISO/IEC JTC1/SC22/WG5, the technical working group for the Fortran language. This part of ISO/IEC 1539 is an auxiliary standard to ISO/IEC 1539 : 1996, which defines the latest revision of the Fortran language, and is the first part of the multipart Fortran family of standards; this part of ISO/IEC 1539 is the third part. The revised language defined by the above standard is informally known as Fortran 95. This part of ISO/IEC 1539 defines a conditional compilation language facility. 2. RATIONALE ------------------------------------------------------- Programmers often maintain multiple copies of code for various operating systems. Maintaining more than one copy of code or relying on edits to the source are error prone methods of obtaining conditional compilation. A conditional compilation language facility permits the programmer to rely on the processor to select blocks of code based on specified conditions. There are many uses for conditional compilation. Writing portable code is one of the most popular uses of conditional compilation. Examples in Annex A show some other uses for conditional compilation. 3. GENERAL --------------------------------------------------------- 1. Scope This part of ISO/IEC 1539 defines facilities for use in Fortran for conditional compilation. This part of ISO/IEC 1539 provides an auxiliary standard for the version of the Fortran language informally known as Fortran 95. The international Standard defining this revision of the Fortran language is ISO/IEC 1539-1 : 1996 "Programming Language Fortran" 2. Normative References The following standard contains provisions which, through reference in this text, constitute provisions of this part of IOS/IEC 1539. At the time of publication, the edition indicated was valid. All standards are subject to revision, and parties to agreements based on this part of IOS/IEC 1539 are encouraged to investigate the possibility of applying the most recent editions of the standard indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. IOS/IEC 1539-1 : 1996, Information technology--Programming Languages--Fortran. 4. THE CONDITIONAL COMPILATION LANGUAGE DEFINITION ----------------- Section CC1 Conditional Compilation The conditional compilation language definition for Fortran consists of nine directives and one option. The one option together with the conditional compilation directives offer the power to select alternative blocks of code for compilation without modifying the source text. In this part of ISO/IEC 1539, sections are numbered CCs, where s is a one or two-digit section number. The notation used in this part of ISO/IEC 1539 is described in Part 1, section 1.6. However, item (4) in Part 1, section 1.6.2 is replace with: (4) Each syntax rule is given a unique identifying number of the form CCRsnn, where s is a one or two-digit section number and nn is a two-digit sequence number within that section. The syntax rules are distributed as appropriate throughout the text, and are referenced by number as needed. Some rules in Section CC2 and CC3 are more fully described in later sections; in such cases, the section number s is the number of the later section where the rule is repeated. Section CC2 High level syntax This section introduces the terms associated with the conditional compilation program. CCR201 coco-program is coco-directive [ coco-directive ] ... CCR202 coco-directive is coco-type-decl-directive or coco-executable-construct or INCLUDE line CCR203 coco-executable-construct is coco-action-directive or coco-if-construct CCR204 coco-action-directive is coco-assignment-directive or coco-error-directive Section CC3 Constants, source form and including text CC3.1 Coco constants CCR301 coco-constant is coco-literal-constant or coco-named-constant CCR302 coco-literal-constant is coco-int-literal-constant or coco-logical-literal-constant CCR303 coco-int-literal-constant is digit-string CCR304 coco-logical-literal-constant is .TRUE. or .FALSE. CCR305 coco-char-literal-constant is ' [ rep-char ] ... ' or " [ rep-char ] ... " CCR306 coco-named-constant is name [digit-string is specified in part 1, R402 of this standard.] [rep-char is specified in part 1, section 4.3.2.1 of this standard.] [A name is specified in part 1, section 3.2.1 of this standard.] CC3.2 Coco source form A coco program is a sequence of one or more lines, organized as coco directives and coco comments. A coco directive is a sequence of one or more complete or partial lines. A line is a sequence of zero or more characters. A coco character context means characters within a coco character literal constant (CCR305). A coco comment may contain any character that may occur in any coco character context. In coco source form, each source line may contain from zero to 132 characters and there are restrictions on where a coco directive (or portion of a coco directive) may appear within a line. In coco source form, blank characters shall not appear within coco lexical tokens other than in a coco character context. Blanks may be inserted freely between coco tokens to improve readability. A sequence of blank characters outside of a coco character context is equivalent to a single blank character. [Lexical token is specified in part 1, section 3.2 of this standard.] A blank shall be used to separate coco names, or coco constants from adjacent keywords, coco names, or coco constants. CC3.2.1 Coco directive start CCR307 coco-dir-start is ?? Constraint: The characters "??" shall be in character positions 1 and 2 of the source line. CC3.2.2 Coco commentary A line that does not start with a coco-dir-start and is not an INCLUDE line is called a coco comment line. Within a coco directive, the character "!" in any character position initiates a coco comment except when it appears within a coco character context. The comment extends to the end of the source line. If the first nonblank character on a line after a coco-dir-start is an "!", the line is also a coco comment line. Lines containing only blanks after a coco-dir-start or containing no characters after a coco-dir-start are also coco comment lines. Note CC3.1 Examples of coco comment lines are: gender = GetRabbitGender(a_rabbit) ! a Fortran comment ?? ! set "system" to "system_A" ?? ?> OPEN(UNIT=6, FILE="system.dependent.name") ?* OPEN(UNIT=6, FILE="sysdpnt.nam") ENDNote CC3.1 CC3.2.3 Coco directive continuation The character "&" is used to indicate that the current coco directive is continued on the next line. The next line shall begin with a coco-dir-start. Coco comment lines shall not be continued; an "&" in a coco comment has no effect. When used for continuation, the "&" is not part of the coco directive. No line shall contain a single "&" as the only nonblank character after a coco-dir-start in a coco directive or as the only nonblank character after the coco-dir-start and before an "!" that initiates a comment. CC3.2.3.1 Coco-noncharacter context continuation In a coco directive, if an "&" not in a coco comment is the last nonblank character on a line or the last nonblank character before an "!" that initiates a comment, the coco directive is continued on the next line. If the first nonblank character after a coco-dir-start on the next coco-noncomment line is an "&", the coco directive continues at the next character following the "&"; otherwise, it continues with the first character position after the coco-dir-start of the next coco-noncomment line. If a coco lexical token is split across the end of a line, the first nonblank character after the coco-dir-start on the first following coco-noncomment line shall be an "&" immediately followed by the successive characters of the split token. Note CC3.2 An example of coco-noncharacter context continuation is: ?? LOGICAL :: TOO_GOOD& ??&_TO_BE_& ??&TRUE = & ?? .FALSE. ! These four lines contain 1 coco directive ENDNote CC3.2 CC3.2.3.2 Coco character context continuation If a coco character context is to be continued, the "&" shall be the last nonblank character on the line and shall not be followed by coco commentary. An "&" shall be the first nonblank character after the coco-dir-start on the next line and the coco directive continues with the next character following the "&". Note CC3.3 An example of coco character context continuation is: ?? ERROR "de& ?? &f& ?? &inately choosing Fortran" ! 3 lines, 1 coco directive ENDNote CC3.3 CC3.2.4 Coco directives A coco directive shall begin with a coco-dir-start. If a coco directive has one or more continuation lines, every line from the start of the coco directive until the end of the coco directive shall begin with a coco-dir-start. A coco directive shall not have more than 39 continuation lines. Note CC3.4 Examples of coco directives are: ?? INTEGER, PARAMETER :: SYSTEM_A = 1 ?? ERROR "system_A = ", SYSTEM_A ?? IF (.FALSE.) THEN ?? ENDIF ENDNote CC3.4 CC3.3 Including source text Additional text may be incorporated into the source text of a coco program during processing. This is accomplished with the INCLUDE line, which has the form INCLUDE char-literal-constant [The INCLUDE line is specified in part 1, section 3.4 of this standard.] Included source text cannot directly or indirectly include itself. An INCLUDE line in a coco FALSE block (CC6.2.2) is not expanded. Any coco-else-if-directive, coco-else-directive and coco-endif-directive shall not appear in included source text unless the matching coco-if-directive appears in the same included source text. Section CC4 Coco type declaration directives Every data object has a type and may have the parameter attribute. The type of a named data object is specified in a type declaration directive. CCR401 coco-type-declaration-directive is coco-type-spec [ , PARAMETER ] :: coco-entity-decl-list CCR402 coco-type-spec is INTEGER or LOGICAL CCR403 coco-entity-decl is coco-object-name [ coco-initialization ] Constraint: A coco-object-name shall not be the same as any other coco-object-name. CCR404 coco-object-name is object-name [Object-name token is specified in part 1, section 5 of this standard.] Constraint: coco-object-name shall appear in a coco-type-declaration-directive before appearing elsewhere in a coco program. CCR405 coco-initialization is = coco-initialization-expr Constraint: The types of the coco-initialization-expr and the coco-type-spec shall either both be integer or both be logical. Constraint: In a coco-type-declaration-directive, if the PARAMETER attribute is specified, a coco-initialization shall appear for every coco-object-name. Note CC4.1 Examples of coco type declaration directives are: ?? INTEGER, PARAMETER :: F77 = 1, F90 = 2, F95 = 3 ?? INTEGER :: FORTRAN_LEVEL = F95 ?? LOGICAL :: DEBUG_PROCEDURE_ENTRY_EXIT ENDNote CC4.1 Section CC5 Coco variables, expressions and assignment directive CC5.1 Coco variables CCR501 coco-variable is coco-variable-name Constraint: coco-variable-name shall not have the PARAMETER attribute. CC5.2 Coco expressions CC5.2.1 Coco primary CCR502 coco-primary is coco-constant or coco-variable or ( coco-expr ) Constraint: A coco-variable shall be defined (CC8.2) before appearing as a coco-primary. CC5.2.2 Level-1 expressions CCR503 coco-add-operand is [ coco-add-operand mult-op ] coco-primary [mult-op is specified in part 1, section 7.1.1.3 of this standard.] CCR504 coco-level-1-expr is [ [ coco-level-1-expr ] add-op ] coco-add-operand [add-op is specified in part 1, section 7.1.1.3 of this standard.] CC5.2.3 Level-2 expressions CCR505 coco-level-2-expr is [ coco-level-1-expr rel-op ] coco-level-1-expr [rel-op is specified in part 1, section 7.1.1.5 of this standard.] CC5.2.4 Level-3 expressions CCR506 coco-and-operand is [ not-op ] coco-level-2-expr [not-op is specified in part 1, section 7.1.1.6 of this standard.] CCR507 coco-or-operand is [ coco-or-operand and-op ] coco-and-operand [and-op is specified in part 1, section 7.1.1.6 of this standard.] CCR508 coco-equiv-operand is [ coco-equiv-operand or-op ] coco-or-operand [or-op is specified in part 1, section 7.1.1.6 of this standard.] CCR509 coco-level-3-expr is [ coco-level-3-expr equiv-op ] coco-equiv-operand [equiv-op is specified in part 1, section 7.1.1.6 of this standard.] CC5.2.5 General form of a coco expression CCR510 coco-expr is coco-level-3-expr CC5.3 Data type of a coco expression The data type of a coco expression is either Integer or Logical. [The data type of a coco expression is specified in part 1, table 7.1 of this standard.] CCR511 coco-logical-expr is coco-expr Constraint: coco-logical-expr shall be type logical. CC5.4 Coco initialization expression CCR512 coco-initialization-expr is coco-expr Constraint: A coco-initialization-expr shall not have a coco-variable as a coco-primary. CC5.5 Coco assignment directive A coco variable may be defined or redefined by execution of a coco assignment directive. CCR513 coco-assignment-directive is coco-variable = coco-expr where coco-variable is defined in CCR501 and coco-expr is defined in CCR510. In a coco assignment directive, the types of coco-variable and coco-expr shall either both be integer or both be logical. Note CC5.2 Examples of coco assignment directives are: ?? DEBUG_LEVEL = DEBUG_LEVEL + 1 ?? IS_COMPANY_X_MACHINE = (SYSTEM == SYS_E) .OR. (SYSTEM == SYS_F) ?? PROJECT_LEVEL = FOO_VERSION + LATEST_RELEASE ENDNote CC5.2 Section CC6 Coco execution control and conditional compilation The execution sequence and conditional compilation are controlled by coco if constructs. Note CC6.1 A coco program is not required to contain any coco if constructs, coco error directives or INCLUDE lines. Execution of such a coco program has no effect. ENDNote CC6.1 CC6.1 Coco blocks A coco block is a sequence of coco directives that are treated as a unit. CCR601 coco-block is [ coco-directive ] ... Coco executable constructs may be used to control which coco blocks of a coco program are executed. CC6.2 Coco IF construct The coco IF construct selects for execution no more than one of its constituent coco blocks. This coco block is called the coco TRUE block. The remainder of the coco blocks in a coco IF construct, if any, are selected to be ignored by the processor. These coco blocks are called coco FALSE blocks. CC6.2.1 Form of the coco IF construct CCR602 coco-if-construct is coco-if-then-directive coco-block [ coco-else-if-directive coco-block ] ... [ coco-else-directive coco-block ] coco-end-if-directive CCR603 coco-if-then-directive is IF ( coco-logical-expr ) THEN CCR604 coco-else-if-directive is ELSE IF ( coco-logical-expr ) THEN CCR605 coco-else-directive is ELSE CCR606 coco-end-if-directive is END IF Note CC6.2 An example of two coco if constructs, one nested within the other, is: ?? IF (IS_COMPANY_X_MACHINE) THEN ?? IF (FORTRAN_LEVEL == F95) THEN PURE FUNCTION GET_RABBIT_WEIGHT(A_RABBIT) RESULT(WEIGHT) TYPE (RABBIT), INTENT(IN) :: A_RABBIT ?? ELSEIF (FORTRAN_LEVEL == F90) THEN FUNCTION GET_RABBIT_WEIGHT(A_RABBIT) RESULT(WEIGHT) TYPE (RABBIT) :: A_RABBIT ?? ELSE ?? ERROR "We do not have a FORTRAN 77 product from company X" ?? ENDIF ?? ELSE FUNCTION GET_RABBIT_WEIGHT() RESULT(WEIGHT) ! Only have Fortran 90 derived types with company X, so ! return a weight of 1 for now ?? ENDIF ENDNote CC6.2 CC6.2.2 Execution of an IF construct At most one of the coco blocks in the coco IF construct is executed. If there is a coco ELSE directive in the construct, exactly one of the coco blocks in the construct will be executed. The coco logical expressions are evaluated in the order of their appearance in the construct until a true value is found or a coco ELSE directive or coco END IF directive is encountered. If a true value or a coco ELSE directive is found, the coco block immediately following is executed and this completes the execution of the construct. The coco logical expressions in any remaining coco ELSE IF directives of the coco IF construct are not evaluated. If none of the evaluated expressions are true and there is no coco ELSE directive, the execution of the construct is completed without the execution of any coco block within the construct. Execution of a coco END IF directive has no effect. CC6.2.2.1 Execution of a coco TRUE block Source lines contained in a coco TRUE block are selected as lines for noncoco processing. Note CC6.3 Although noncoco processing generally refers to Fortran processing, it is not required that the lines contained in a coco TRUE block are valid Fortran source text. ENDNote CC6.3 CC6.2.2.2 Execution of a coco FALSE block Source lines contained in a coco FALSE block are selected as lines to be ignored by noncoco processing. Note CC6.4 If a processor offers an output file as a result of coco processing, possible options on the handling of coco directive lines and lines in a coco FALSE block are: (1) delete them, (2) replace them with blank lines, (3) replace them with a "!" in character position 1 followed by the original source line shifted one to the right, or (4) replace them with a "!" in character position 1 followed by the the characters starting from character position 2 of the original source line. All other lines could be copied without modification into the output file. ENDNote CC6.4 Section CC7 Coco error directive and coco stop directive CCR701 coco-error-directive is ERROR [ coco-output-item-list ] CCR702 coco-output-item is coco-expr or coco-char-literal-constant Execution of a coco ERROR directive specifies that an error has occurred during coco processing. At the time of execution of a coco ERROR directive, the output-item-list, if any, is available in a processor-dependent manner. Note CC7.1 Examples of the coco error directive are: ?? ERROR "system shall be set to 'sys1' or 'sys2'" ?? ERROR "system = ", SYSTEM ?? ERROR ENDNote CC7.1 CCR703 coco-stop-directive is STOP Execution of a coco STOP directive halts coco processing. Section CC8 Scope and definition of coco variables CC8.1 Scope of coco variables Coco variables have the scope of the coco program in which they are declared. CC8.2 Events that cause coco variables to become defined Coco variables become defined as follows: (1) Execution of a coco assignment directive causes the coco variable that precedes the equals to become defined. (2) Execution of a coco initialization in a coco type declaration directive causes the coco variable that precedes the equals to become defined. (3) Execution of the coco-set-option (Section CC10) causes the coco variable to become defined. Section CC9 Coco program conformance A coco program is a standard-conforming coco program if it uses only those forms and relationships herein and if the program has an interpretation according to this standard. A coco processor conforms to this standard if: (1) It executes any standard-conforming coco program in a manner that fulfills the interpretations herein, subject to any limits that the processor may impose on the size and complexity of the coco program. (2) It contains the capability to detect and report the use within a submitted coco program of an additional form or relationship that is not permitted by the numbered syntax rules or their associated constraints. (3) It contains the capability to detect and report the use within a submitted coco program of source form not permitted by Section CC3. (4) It contains the capability to detect and report the reason for rejecting a submitted program. Section CC10 The coco SET option There is one coco option--the coco-set-option. A processor shall supply at least one method of recognizing the coco-set-option separate from the coco program. Note CC10.1 The invocation line may be the chosen method of communicating the coco-set-option to the processor. Another method of communicating the coco-set-option to the processor could be a coco input file. ENDNote CC10.1 The coco-set-option is a method of (1) documenting the value of a coco PARAMETER; (2) assigning an initial value to a coco variable (CCR501); (3) overriding the initial value assigned to a coco variable in a coco initialization expression (CCR512) without editing the coco program. Note CC10.2 Recall that a coco variable shall not have the PARAMETER attribute. ENDNote CC10.2 CCR1001 coco-set-option is coco-set-option-variable=coco-set-option-literal-constant [ coco-set-option-variable=coco-set-option-literal-constant ] ... or processor-defined-coco-set-option CCR1002 coco-set-option-variable is coco-variable CCR1003 coco-set-option-literal-constant is coco-literal-constant Constraint: A processor-defined-coco-set-option shall contain a coco-set-option-variable and a coco-set-option-literal-constant. Constraint: The coco-set-option-variable must be a coco variable declared in the coco type declaration directive. Constraint: The type of the coco-set-option-variable shall match the type of the coco-set-option-literal-constant. Constraint: If the coco-set-option-variable has the PARAMETER attribute, the value of the coco-set-option-literal-constant shall match the value supplied in the coco type declaration directive. Constaint: If the coco-set-option-variable appears in the coco program as the coco variable in a coco assignment directive, it shall appear at least once in a previous coco executable construct. The coco-set-option minimally consists of a coco-set-option-variable and a coco-set-option-literal-constant. A processor may supply additional representations for the coco logical literal constant; for example, the characters 'T' or 'F' could be used to represent .TRUE. or .FALSE. respectively. In this case it is as if .TRUE. or .FALSE. were specified as the coco-set-option-literal-constant. The coco-set-option acts as if a coco assignment directive (CCR513)-- which consists of the coco-set-option-variable as the coco variable and the coco-set-option-literal-constant as the coco expression (CCR510)--were placed immediately following the coco type declaration directive that declared the coco-set-option-variable. Note CC10.4 The value assigned to a coco variable with the coco-set-option shall not override the value assigned to a coco variable with the coco assignment directive. ENDNote CC10.4 Annex CCA : EXAMPLES ------------------------------------------------- This annex includes two examples illustrating the use of facilities conformant with this part of ISO/IEC 1539. The first example uses conditional compilation to facilitate the editing of a large block comment. The second example uses conditional compilation to provide debugging information upon entering and exiting procedures. Note, the conditional compilation directives in this example could be automatically generated. Each example contains a conditional compilation program and a possible output file from conditional compilation processing. --- initial text ------------------------------------------ ! EXAMPLE 1 shows a possible shift file for output ?? LOGICAL :: MODIFYING_HEADER_COMMENT = .FALSE. ?? IF (.NOT. MODIFYING_HEADER_COMMENT) THEN One convenient use of conditional compilation is the ability to write large comments that span across many lines without requiring each line to start with a "!". Since conditional compilation specifies blocks of lines to be skipped over by the processor, this whole paragraph can be written and modified without the overhead of making sure that each line is a Fortran comment. One can imagine this use of conditional compilation for header comments preceding Fortran programs, modules and procedures. ?? ENDIF --- possible text output from conditional compilation processing --- ! EXAMPLE 1 shows a possible shift file for output !?>?? LOGICAL :: MODIFYING_HEADER_COMMENT = .FALSE. !?>?? IF (.NOT. MODIFYING_HEADER_COMMENT) THEN !?> !?>One convenient use of conditional compilation is the !?>ability to write large comments that span across many !?>lines without requiring each line to start with a "!". !?>Since conditional compilation specifies blocks of lines !?>to be skipped over by the processor, this whole paragraph !?>can be written and modified without the overhead of !?>making sure that each line is a Fortran comment. !?> !?>One can imagine this use of conditional compilation for !?>header comments preceding Fortran programs, modules and !?>procedures. !?> !?>?? ENDIF --- initial text ------------------------------------------ ! EXAMPLE 2 shows a possible short file for output ?? LOGICAL :: DEBUG_PROC_NAME = .FALSE. ?? LOGICAL :: DEBUG_PROC_ARGS = .FALSE. ?? ! Make sure to debug the procedure name if debugging the arguments ?? DEBUG_PROC_NAME = DEBUG_PROC_NAME .OR. DEBUG_PROC_ARGS SUBROUTINE INTSWAP (LEFT, RIGHT) INTEGER, INTENT(INOUT) :: LEFT, RIGHT INTEGER :: WRONG ?? IF (DEBUG_PROC_NAME) THEN PRINT *, "Entering IntSwap" ?? ENDIF ?? IF (DEBUG_PROC_ARGS) THEN PRINT *, " IntSwap(in):left = ", LEFT PRINT *, " IntSwap(in):right = ", RIGHT ?? ENDIF WRONG = RIGHT LEFT = RIGHT RIGHT = WRONG ?? IF (DEBUG_PROC_ARGS) THEN PRINT *, " IntSwap(out):left = ", LEFT PRINT *, " IntSwap(out):right = ", RIGHT ?? ENDIF ?? IF (DEBUG_PROC_NAME) THEN PRINT *, "Exiting IntSwap" ?? ENDIF ENDSUBROUTINE INTSWAP --- possible text output from conditional compilation processing --- ! EXAMPLE 2 shows a possible short file for output SUBROUTINE INTSWAP (LEFT, RIGHT) INTEGER, INTENT(INOUT) :: LEFT, RIGHT INTEGER :: WRONG WRONG = RIGHT LEFT = RIGHT RIGHT = WRONG ENDSUBROUTINE INTSWAP --=====================_846301917==_--