tar -zxvf g95-x86-linux.tgz
ln -s $PWD/g95-install/bin/*g95* ~/bin/g95
| -c | Compile only, do not run the linker. |
| -o | Specify the name of the output file, either an object file or the executable. |
Files ending in uppercase letters are preprocessed with the C preprocessor by default, files ending in lowercase letters are not preprocessed by default.
Files ending in ".f", ".F", ".for", and ".FOR" are assumed to be fixed form source compatible with old f77 files. Files ending in ".f90", ".F90", ".f95", ".F95", ".f03" and ".F03" are assumed to be free source form.
Simple examples:
| g95 -c hello.f90 | Compiles hello.f90 to an object file named hello.o. |
| g95 hello.f90 | Compiles hello.f90 and links it to produce an executable a.out. |
| g95 -c h1.f90 h2.f90 h3.f90 | Compiles multiple source files. If all goes well, object files h1.o, h2.o and h3.o are created. |
| g95 -o hello h1.f90 h2.f90 h3.f90 | Compiles multiple source files and links them together to an executable file named 'hello'. |
| -cpp | Force the input files to be run through the C preprocessor |
| -no-cpp | Prevent the input files from being preprocessed |
| -Dname[=value] | Define a preprocessor macro |
| -Uname | Undefine a preprocessor macro |
| -E | Show preprocessed source only |
| -Idirectory | Append 'directory' to the include and module files search path. Files are searched for in various directories in this order: Directory of the main source file, the current directory, directories specified by -I, directories specified in the G95_INCLUDE_PATH environment variable and finally the system directories. |
| -traditional | Performs traditional C preprocessing (default) |
| -nontraditional | Performs modern C preprocessing |
| -Wall | Enable most warning messages |
| -Werror | Change warnings into an errors |
| -Werror=x | Change warning x into an error |
| -Wextra | Enable warning not enabled by -Wall |
| -Wglobals | Cross-check procedure use and definition within the same source file. On by default, use -Wno-globals to disable. |
| -Wimplicit-none | Same as -fimplicit-none |
| -Wimplicit-interface | Warn about using an implicit interface |
| -Wline-truncation | Warn about truncated source lines |
| -Wmissing-intent | Warn about missing intents on formal arguments |
| -Wobsolescent | Warn about obsolescent constructs |
| -Wno=numbers | Disable a comma separated list of warning numbers |
| -Wuninitialized | Warn about variables used before initialized. Requires -O2 |
| -Wunused-vars | Warn about unused variables |
| -Wunused-types | Warn about unused module types. Not implied by -Wall |
| -Wunset-vars | Warn about unset variables |
| -Wunused-module-vars | Warn about unused module variables. Useful for ONLY clauses |
| -Wunused-module-procs | Warn about unused module procedures. Useful for ONLY clauses |
| -Wunused-parameter | Warn about unused parameters. Not implied by -Wall |
| -Wprecision-loss | Warn about precision loss in implicit type conversions |
| -fbackslash | Interpret backslashes in character constants as escape codes. Use -fno-backslash to treat backslashes literally. |
| -fd-comment | Make D lines executable statements in fixed form. |
| -fdollar-ok | Allow dollar signs in entity names |
| -fendian= | Force the endianness of unformatted reads and writes. The value must be 'big' or 'little'. Overrides environment variables. |
| -ffixed-form | Assume that the source file is fixed form |
| -ffixed-line-length-132 | 132 character line width in fixed mode |
| -ffixed-line-length-80 | 80 character line width in fixed mode |
| -ffree-form | Assume that the source file is free form |
| -ffree-line-length-huge | Allow very large source lines (10k) |
| -fimplicit-none | Specify that no implicit typing is allowed, unless overridden by explicit IMPLICIT statements |
| -fintrinsic-extensions | Enable g95-specific intrinsic functions even in a -std= mode |
| -fintrinsic-extensions=proc1,proc2,... | Include selected intrinsic functions even in a -std= mode. The list is comma-separated and case insensitive. |
| -fmod=directory | Put module files in directory |
| -fmodule-private | Set default accessibility of module-entities to PRIVATE |
| -fmultiple-save | Allow the SAVE attribute to be specified multiple times |
| -fone-error | Force compilation to stop after the first error. |
| -ftr15581 | Enable the TR15581 allocatable array extensions even in -std=F or -std=f95 modes. |
| -M | Produce a Makefile dependency line on standard output |
| -std=F | Warn about non-F features |
| -std=f2003 | Strict fortran 2003 checking |
| -std=f95 | Strict fortran 95 checking |
| -i4 | Set kinds of integers without specification to kind=4 (32 bits). Default kinds are unchanged. |
| -i8 | Set kinds of integers without specification to kind=8 (64 bits). Default kinds are unchanged. |
| -r8 | Set kinds of reals without kind specifications to double precision |
| -d8 | Implies -i8 and -r8. |
| -fbounds-check | Check array and substring bounds at runtime |
| -fcase-upper | Make all public symbols uppercase |
| -fleading-underscore | Add a leading underscore to public names |
| -fonetrip | Execute DO-loops at least once. (Buggy fortran 66) |
| -fpack-derived | Try to layout derived types as compact as possible. Requires less memory, but may be slower |
| -fqkind=n | Set the kind for a real with the 'q' exponent to n |
| -fsecond-underscore | Append a second trailing underscore in names having an underscore (default). Use -fno-second-underscore to suppress. |
| -fshort-circuit | Cause the .AND. and .OR. operators to not compute the second operand if the value of the expression is known from the first operand. |
| -fsloppy-char | Suppress errors when writing non-character data to character descriptors |
| -fstatic | Put local variables in static memory where possible. This is not the same as linking things statically (-static). |
| -ftrace | '-ftrace=frame' will insert code to allow stack tracebacks on abnormal end of program. This will slow down your program. '-ftrace=full' additionally allows finding the line number of arithmetic exceptions (slower). Default is '-ftrace=none'. |
| -funderscoring | Append a trailing underscore in global names (default). Use -fno-underscoring to suppress. |
| -max-frame-size=n | How large a single stack frame will get before arrays are allocated dynamically |
| -finteger=n | Initialize uninitialized scalar integer variables to n |
| -flogical= | Initialize uninitialized scalar logical variables. Legal values are none, true and false. |
| -freal= | Initialize uninitialized scalar real and complex variables. Legal values are none, zero, nan, inf, +inf and -inf. |
| -fpointer= | Initialize scalar pointers. Legal values are none, null and invalid. |
| -fround= | Controls compile-time rounding. Legal values are nearest, plus, minus and zero. Default is round to nearest, plus is round to plus infinity, minus is minus infinity, zero is towards zero. |
| -fzero | Initialize numeric types to zero, logical values to false and pointers to null. The other initialization options override this one. |
The values of the various variables are always strings, but the strings can be interpreted as integers or boolean truth values. Only the first character of a boolean is examined and must be 't', 'f', 'y', 'n', '1' or '0' (uppercase OK too). If a value is bad, no error is issued and the default is used.
| G95_STDIN_UNIT | Integer | Unit number that will be preconnected to standard input. No preconnection if negative, default is 5. |
| G95_STDOUT_UNIT | Integer | Unit number that will be preconnected to standard output. No preconnection if negative, default is 6. |
| G95_STDERR_UNIT | Integer | Unit number that will be preconnected to standard error. No preconnection if negative, default is 0. |
| G95_USE_STDERR | Boolean | Sends library output to standard error instead of standard output. Default is Yes. |
| G95_ENDIAN | String | Endian format to use for I/O of unformatted data. Values are BIG, LITTLE or NATIVE. Default is NATIVE. |
| G95_CR | Boolean | Output carriage returns for formatted sequential records. Default true on windows, false elsewhere. |
| G95_IGNORE_CR | Boolean | Treat a carriage return-linefeed as a record marker instead of just a linefeed. Default true. |
| G95_IGNORE_ENDFILE | Boolean | Ignore attempts to read past the ENDFILE record in sequential access mode. Default false |
| G95_TMPDIR | String | Directory for scratch files. Overrides the TMP environment variable. If TMP is not set /var/tmp is used. No default |
| G95_UNBUFFERED_ALL | Boolean | If TRUE, all output is unbuffered. This will slow down large writes but can be useful for forcing data to be displayed immediately. Default is False. |
| G95_SHOW_LOCUS | Boolean | If TRUE, print filename and line number where runtime errors happen. Default is Yes. |
| G95_OPTIONAL_PLUS | Boolean | Print optional plus signs in numbers where permitted. Default FALSE. |
| G95_DEFAULT_RECL | Integer | Default maximum record length for sequential files. Most useful for adjusting line length of preconnected units. Default is 50000000. |
| G95_LIST_SEPARATOR | String | Separator to use when writing list output. May contain any number of spaces and at most one comma. Default is a single space. |
| G95_LIST_EXP | Integer | Last power of ten which does not use exponential format for list output. Default 6. |
| G95_COMMA | Boolean | Use a comma character as the default decimal point for I/O. Default false. |
| G95_EXPAND_UNPRINTABLE | Boolean | For formatted output, print otherwise unprintable characters with \-sequences. Default No. |
| G95_QUIET | Boolean | Suppress bell characters (\a) in formatted output. Default No. |
| G95_SYSTEM_CLOCK | Integer | Number of ticks per second reported by the SYSTEM_CLOCK() intrinsic in microseconds. Zero disables the clock. Default 100000. |
| G95_SEED_RNG | Boolean | If true, seeds the random number generator with a new seed when the program is run. Default false. |
| G95_MINUS_ZERO | Boolean | If true, prints minus zero without a minus sign in formatted (non-list) output, contrary to the standard. Default FALSE. |
| G95_ABORT | Boolean | If true, dumps core on abnormal program end. Useful for finding the locus of the problem. Default FALSE. |
| G95_MEM_INIT | String | How to initialize allocated memory. Default value is NONE for no initialization (faster), NAN for a Not-a-Number with the mantissa 0x40f95 or a custom hexadecimal value. |
| G95_MEM_SEGMENTS | Integer | Maximum number of still-allocated memory segments to display when program ends. 0 means show none, less than 0 means show all. Default 25 |
| G95_MEM_MAXALLOC | Boolean | If true, shows the maximum number of bytes allocated in user memory during the program run. Default No. |
| G95_MEM_MXFAST | Integer | Maximum request size for handing requests in from fastbins. Fastbins are quicker but fragment more easily. Default 64 bytes. |
| G95_MEM_TRIM_THRESHOLD | Integer | Amount of top-most memory to keep around until it is returned to the operating system. -1 prevents returning memory to the system. Useful in long-lived programs. Default 262144. |
| G95_MEM_TOP_PAD | Integer | Extra space to allocate when getting memory from the OS. Can speed up future requests. Default 0. |
| G95_SIGHUP | String | Whether the program will IGNORE, ABORT or SUSPEND on SIGHUP. Default ABORT. |
| G95_SIGINT | String | Whether the program will IGNORE or ABORT or SUSPEND on SIGINT. Default ABORT |
| G95_FPU_ROUND | String | Set floating point rounding mode. Values are NEAREST, UP, DOWN, ZERO. Default is NEAREST. |
| G95_FPU_PRECISION | String | Precision of intermediate results. Value can be 24, 53 and 64. Default 64. Only available on x86 and IA64 compatibles. |
| G95_FPU_DENORMAL | Boolean | Raise a floating point exception when denormal numbers are encountered. Default no. |
| G95_FPU_INVALID | Boolean | Raise a floating point exception on an invalid operation. Default No. |
| G95_FPU_ZERODIV | Boolean | Raise a floating point exception when dividing by zero. Default No. |
| G95_FPU_OVERFLOW | Boolean | Raise a floating point exception on overflow. Default No. |
| G95_FPU_UNDERFLOW | Boolean | Raise a floating point exception on underflow. Default No. |
| G95_FPU_INEXACT | Boolean | Raise a floating point exception on precision loss. Default No |
| G95_FPU_EXCEPTIONS | Boolean | Whether masked floating point exceptions should be shown after the program ends. Default No |
| G95_UNIT_x | String | Overrides the default unit name for unit x. |
| G95_UNBUFFERED_x | Boolean | If true, unit x is unbuffered |
| G95_UNIT_ENDIAN_x | String | Sets the endianness of an individual unit. The value can be "big" or "little". Takes precedence over G95_ENDIAN |
| -2 | End of record |
| -1 | End of file |
| 0 | Successful return |
| Operating system errno codes (1 - 199) | |
| 200 | Conflicting statement options |
| 201 | Bad statement option |
| 202 | Missing statement option |
| 203 | File already opened in another unit |
| 204 | Unattached unit |
| 205 | FORMAT error |
| 206 | Incorrect ACTION specified |
| 207 | Read past ENDFILE record |
| 208 | Bad value during read |
| 209 | Numeric overflow on read |
| 210 | Out of memory |
| 211 | Array already allocated |
| 212 | Deallocated a bad pointer |
| 214 | Corrupt record in unformatted sequential-access file |
| 215 | Reading more data than the record size (RECL) |
| 216 | Writing more data than the record size (RECL) |
Use the 'nm' program to look at the .o files being produce by both compilers.
G95 folds public names to lowercase as well, unless -fupper-case is given, in which case everything will be upper case. Module names are represented as module-name_MP_name.
After linking, there are two main cases: Fortran calling C subroutines and C calling fortran subroutines.
For C calling fortran subroutines, the fortran subroutines will often call fortran library subroutines that expect the heap to be initialized in some way. To force a manual initialization from C, call g95_runtime_start() to initialize the fortran library and g95_runtime_stop() when done. The prototype of the g95_runtime_start() is:
void g95_runtime_start(int argc, char *argv[]);The library has to be able to process command-line options. If this is awkward to do and your program doesn't have a need for command-line arguments, pass argc=0 and argv=NULL.
On OSX/Tiger, include '-lSystemStubs' when using g95 to run the linker and linking objects files compiled by gcc.
Information on OpenGL binding can be found at Nick Yasko's G95/OpenGL page.