This allows valid FPE-using programs to be compiled using only #pragma float, with no changes needed to the code itself.
The slot-setting code is only generated if the slot is 1..7, and even then it can be overridden by calling setfpeslot(), so this should not cause compatibility problems for existing code.
It now covers pretty much all the new features, as well as addressing the errata from the release notes and some other miscellaneous issues. The early chapters still need to be updated to refer to a hard disk installation, rather than being based on running it from floppies (which is no longer supported). I'm sure more proofreading and editing would also be beneficial.
This is the ORCA/C 2.0 manual from Opus ][, re-saved in the modern Microsoft Word format and adjusted to fix some formatting issues. In particular, the embedded images needed to be converted to formats that current versions of Word support. The result is very close to the original version, although the pagination winds up slightly different in some places.
When the lint check for undefined variables was enabled, a "lint: unused variable: @struct" would be produced for any function returning a struct or union, due to the special static variable that is created to hold the return value. That spurious lint message is now suppressed.
This prohibits initializers in "extern" declarations within a function, and in the parameter declarations of non-prototyped functions.
Here are examples illustrating these cases:
int main(void) {
extern int i = 50;
}
void f(i)
int i = 60;
{
}
We now recognize cases where the same value needs to be pushed for several consecutive words, so it is more efficient to load it into a register and push that rather than just using PEA instructions.
This covers code like the following:
int main(void) {
auto int a[20];
static int *p = &a[5];
}
Previously, this would compile without error, and then either give a linker error or be linked to refer to the global symbol "a" (if there was one).
Any stack-allocated array must be < 32KB, so we can use the same approach as in the small memory model to compute indexes for it (which is considerably more efficient than the large-memory-model code).
The code generator never generates this code sequence (and did not do so even prior to the last commit), so having a peephole optimization for it is pointless.
The new code is smaller and (in the common case where the subtraction does not overflow) faster. It takes advantage of the fact that in overflow cases the carry flag always gets set to the opposite of the sign bit of the result.
This will change a "jump if true" to "jump if false" (or vice versa) and logically negate the condition in certain cases where that generates better code.
An assembly peephole optimization for certain "branch to branch" instructions is also added. (Certain conditionals could generate these.)
