Calling assembly routines from C

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#3239

From: John Clinton Hall
Date: Sat, 01 Dec 1990 05:03

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I am writing a program to be separately assembled to be linked with a C
program.  The assembly part prints a string using the undocumented INT 29h
function call (I do know the dangers of using an undocumented function call).

The Microsoft Mixed Language Programming Guide states, "By default, C
parameters are passed by value, except for arrays, which are passed by
reference."  I will assume that C will pass the "reference" of the array to the
function.  What exactly does it mean by "reference?"  Is it a word pointing
into the data segment, or a segment address with a word pointing into the
segment?

Also, how would I define the function with extern in the C program?  Would I
use:

          extern int29( const char * );
-- 
The highest sounds are hardest to hear.  ## ## ## ##### ##  jhall@wpi.wpi.edu
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Path: arc1-ca.pugleaf.net!utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sdd.hp.com!samsung!crackers!m2c!wpi.WPI.EDU!jhall
From: jhall@wpi.WPI.EDU (John Clinton Hall)
Newsgroups: comp.os.msdos.programmer
Subject: Calling assembly routines from C
Message-ID: <1990Dec1.050322.15678@wpi.WPI.EDU>
Date: 1 Dec 90 05:03:22 GMT
Sender: jhall@wpi.WPI.EDU (John Clinton Hall)
Organization: Worcester Polytechnic Institute
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