dispatch.py

##########################################################################
#
# Copyright 2010 VMware, Inc.
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"""Generate DLL/SO dispatching functions.
""" 


import specs.stdapi as stdapi


def function_pointer_type(function):
    return '__PFN' + function.name.upper()


def function_pointer_value(function):
    return '__' + function.name + '_ptr'


class Dispatcher:

    def header(self):
        # Must be implemented by derived classes, which should define, declare,
        # or implement something like:
        #
        #  typedef void (*__PROC)(void);
        #
        #  static __PROC __getPublicProcAddress(const char *name);
        #  static __PROC __getPrivateProcAddress(const char *name);
        #
        raise NotImplementedError

    def dispatch_api(self, api):
        for function in api.functions:
            self.dispatch_function(function)
        
        # define standard name aliases for convenience, but only when not
        # tracing, as that would cause symbol clashing with the tracing
        # functions
        print '#ifdef RETRACE'
        for function in api.functions:
            print '#define %s __%s' % (function.name, function.name)
        print '#endif /* RETRACE */'
        print

    def dispatch_function(self, function):
        ptype = function_pointer_type(function)
        pvalue = function_pointer_value(function)
        print 'typedef ' + function.prototype('* %s' % ptype) + ';'
        print 'static %s %s = NULL;' % (ptype, pvalue)
        print
        print 'static inline ' + function.prototype('__' + function.name) + ' {'
        print '    const char *__name = "%s";' % function.name
        if function.type is stdapi.Void:
            ret = ''
        else:
            ret = 'return '
        self.get_true_pointer(function)
        print '    %s%s(%s);' % (ret, pvalue, ', '.join([str(arg.name) for arg in function.args]))
        print '}'
        print

    def is_public_function(self, function):
        return True

    def get_true_pointer(self, function):
        ptype = function_pointer_type(function)
        pvalue = function_pointer_value(function)
        if self.is_public_function(function):
            get_proc_address = '__getPublicProcAddress'
        else:
            get_proc_address = '__getPrivateProcAddress'
        print '    if (!%s) {' % (pvalue,)
        print '        %s = (%s)%s(__name);' % (pvalue, ptype, get_proc_address)
        print '        if (!%s) {' % (pvalue,)
        self.fail_function(function)
        print '        }'
        print '    }'

    def fail_function(self, function):
        if function.type is stdapi.Void or function.fail is not None:
            print r'            os::log("warning: ignoring call to unavailable function %s\n", __name);'
            if function.type is stdapi.Void:
                assert function.fail is None
                print '            return;' 
            else:
                assert function.fail is not None
                print '            return %s;' % function.fail
        else:
            print r'            os::log("error: unavailable function %s\n", __name);'
            print r'            os::abort();'