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Fix & improve the MS-DOS build using MSVC compiler (3/4) - #823
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This is a superset of the previous ignored globs. The existing entries are now categorised, and the following additional globs are ignored: - lessmsg.inc Automatically generated by distfiles make target - *.exe Executables on DOS, OS/2, and Windows systems - *.obj Object files for some DOS, OS/2, and Windows compilers - *.bak, *.log, *.tmp Backup, log, and temporary files
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Appears to be a relic from when less supported pre-ANSI C and had to choose between `void *` and `char *`.
Another apparent relic from when less supported pre-ANSI C and supported K&R-compatible prototype macros.
Appears to be for planned but never implemented wide-character support. It's never enabled anywhere, and if it were it only enables some (now removed) upper/lower to/is macros. Even that's not true as those macros are gated by `HAVE_WCTYPE` (no `_H` suffix) which isn't defined.
Renames the `less` target to `less.exe` so that incremental build works. Previously every invocation would relink `less.exe` as a `less` file is not output by the Makefile target. Don't suppress error on copying defines.ds to defines.h as this is a real problem that will break the build or give unexpected results. Suppress error output on failing to delete files as this is harmless; it's effectively always going to be because they don't exist. Add missing ".obj" file extension to the Makefile suffix list. Improves documentation and readability of the Makefile.
Auditing the codebase for usage of `ssize_t`` doesn't show any issues with the narrowing of the datatype from 32/64-bits on newer systems.
less depends on non-ANSI library names so this option breaks the build. Also remove the pre-processor definitions mapping non-ANSI library names to their ANSI equivalents as MSVC takes care of this. Only a subset were even valid; many are `stdlib` functions whose name hasn't changed.
All six compiler warnings are `C4761`: `integral size mismatch in argument; conversion supplied` The fix is to add explicit casts for arguments narrowed due to `int` being a 16-bit data type.
Modern less has a lot more static data than historic versions. Under the segmented memory model all near static data plus the stack must fit into a single 64KB data segment (`DGROUP`). By default the compiler allocates static data >= 256 bytes in a far data segment. Change this to be much more aggressive, using >= 16 bytes as the size threshold, so we can fit what's left in the `DGROUP` segment. This is safe under the large memory model as all data pointers are far by default.
The `clreol()` function isn't defined in the MSVC DOS runtime. Use the existing `clear_eol()` function which handles the runtime differences.
It won't ever be called as the call sites are all unreachable, but the linker still requires a symbol.
The MSVC DOS runtime doesn't implement POSIX `sleep()` so we provide our own implementation. Just perform a busy-wait given there's no scheduler to yield to anyway.
The default of 2KB is woefully inadequate for modern less. With this change we actually have a build and resulting binary that works.
The default is 8086, which continues to work but is positively ancient. Targeting at least 80386 lets us reduce the binary size a bit and also probably improves performance (likely imperceptible on modern CPUs). The binary size reduction is ~12KB. For people who really need to run on pre-386 processors the argument can be removed at the cost of a slightly larger binary.
It's unnecessary for text-mode only functions, which is all less uses, and saves another ~12KB from the binary.
Results in slightly faster code and a small binary size saving (~0.5KB).
Decompresses with a tiny stub loader at runtime. Performance impact is effectively zero on all but the oldest systems, but space savings are significant; around ~41KB currently, bringing the binary under 200KB.
I doubt they've been used (or tested) in at least a decade. They can still be customised, but let's not provide a untested configuration.
They're only used on DOS builds so don't include them on other targets.
Might as well since it's available and consistent with what we do for other targets where the runtime provides this function.
The compiler is expected to always be `cl` which makes the indirection provided by the `CC` variable redundant. The includes can be resolved through the `INCLUDE` environment variable and the libraries by the `LIB` environment variable, both set by the `MSVCVARS.BAT` batch file.
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This PR fixes the MS-DOS build of less when building as a 16-bit executable using Microsoft Visual C++. In addition to the required fixes to enable a successful build, it also adds several improvements to the compilation and linking process for a smaller and faster binary. Finally, it significantly improves the documentation on the build requirements and steps so others can more easily perform their own build.
Further details are available in each commit description. This PR is based on top of PR #822. A copy of the build output with these changes is attached along with the resulting statically linked binary if anyone wishes to test it themselves.
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less.exe)