Intel XENIX 286 Programmers Guide (86) - Tenox.tc

XENIX Programming cc: C Compiler
The following example is from a middle model compilation:
int near foo();
This does a near call in an otherwise far (calling) program.
Since there is no type checking between items in separate source files, the near and far
keywords should be used with great care.
The pascal and fortran Keywords
The pascal and fortran keywords may be considered synonymous as they both invoke the
PL/M protocol. The Pascal keyword can be used to either call routines compiled with
the PL/M protocol or compile subroutines with the PL/M protocol.
The assembly language programm ing differences between C and Pascal are as follows:
• Any external Pascal identifiers are mapped to uppercase; underscores (_) are used.
This is true for both global variables and function/procedure names.
• In C, the programmer must readjust the stack pointer after making a call to a
routine. In Pascal, this is not necessary since all calls to routines readjust the
stack before they return a value.
• Conventions for returning floating-point numbers and structured items differ
between C and Pascal. In C, the return value is stored in a static buffer (AX if
the point er is 16 bits, AX-DX if the pointer is far or huge) and the address of this
buffer is passed to the calling routine. In Pascal, space is reserved on the stack
for this return value and a near pointer is passed to the called routine as a hidden
parameter.
Finally, the protocol for passing parameters differs between C and Pascal. In C the
number of parameters is not fixed; the C compiler pushes the parameters from right to
left. In Pascal, since the number of parameters is fixed, the PL/M protocol dictates
that the parameters are pushed from left to right.
The pascal keyword is used in the following form:
int pascal addcol();
where addcol is a function that is to be compiled using the PL/M protocol.
Creating Programs from Assembly Language Source Files
Use the cc command to create executable programs from a combination of C source
files (files ending in .c) and 8086/286 assembly language source files (files ending in .s).
Refer to Chapter 7, "as: Assembler."
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