[phx]

Originally Posted by kerravon

Did amiga.lib exist in the first release of the Amiga SDK issued after the Amiga 1000 was released?

I think so. Although many compilers already provided their own amiga.lib (with the same functionality).

In order to execute Read(), were you nominally required to
#include <clib/dos_protos.h>

Yes. It defines the prototypes for the dos.library functions as well as the data types and structures used in the calls.

(and did that exist in the first SDK?)

No. The first SDK was long before C90 existed. So it wasn't that common to use prototypes for functions you call. The Kickstart 1.3 SDK was still missing them.

I'm thinking that I would like to have the above header file, but make it:

#define Read(a, b, c) DOSBase->Read(a,b,c)

That wouldn't work. There is no "Read" in the DOSBase structure. If want to know the details: Every shared library has a Base structure, like DOSBase, which stores some, mostly internal, data for the library. Invisible for C there is a jump-table in front of this structure in memory. For example at offset -42 relative to DOSBase you will find the vector "jmp ReadFunctionInROM", which jumps to the actual Read() function which is valid for your current OS version. Each vector has 6 bytes (jmp-instruction and 32-bit destination address). That's where amiga.lib comes into play. It defines assembler stub functions like:

        xref    _DOSBase

        xdef    _Read
_Read:
        movem.l d2-d3/a6,-(sp)
        movem.l 16(sp),d1-d3
        move.l  _DOSBase,a6
        jsr     -42(a6)
        movem.l (sp)+,d2-d3/a6
        rts

Which saves/restores non-volatile registers for the function call (d2, d3, a6), loads the C arguments from stack into the required registers for the Read() function, and finally calls its vector relative to DOSBase in register a6.

Originally Posted by kerravon

vbccm68k -gas -I . -I ../src -S -o amistrt.s amistrt.c
error 5: Unknown Flag <-S>

-S is a frontend option for vc to generate assembler code. The compiler itself always generates assembler output. So not needed here.

vbccm68k -gas -I . -I ../src -o amistrt.s amistrt.c
error 3: Flag <-o> needs string

That would be the frontend syntax again. The option in the compiler is different. It is "-o=name". Also note that you may want to enable optimisations at some point (-O=991 would be -O1 from the frontend, refer to the documentation for all optimiser flags).