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-*- mode: outline; coding: utf-8 -*-
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* Caller vs callee.
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If routine A calls routine B then routine A is the caller and routine B is the
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callee. i.e. the caller is the routine which is calling the callee.
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The routine that initiates the call is the caller and the routine that is
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being called is is the callee.
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* Argument vs parameter.
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From the perspective of the caller the thing which is passed is an argument.
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From the perspective of the routine that receives the call, i.e. the callee,
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the thing which is passed is a parameter.
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209
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* Linkage convention.
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A linkage convention is computing term that means an agreement which is made
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between a caller and a callee. The agreement describes:
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- how the caller should pass parameters to the callee
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- what assumptions the callee is allowed to make about the values in the
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machine registers at the moment of the call
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- who should preserve registers which are modified by the callee and/or which
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are important to the caller so that their original values are available
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when the caller needs them
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- how and where registers should be preserved
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- how the callee knows where to return to when it is ready to return to the
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caller
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- how the callee returns a value to the caller if the routine is a function
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(as opposed to a subroutine which has no return value)
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- how a debugger will find the information necessary to obtain a stack trace
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