Apple Newton Utilities User's Guide download pdf (Page 834)

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CHAPTER 23

Endpoint Interface

23-6 About the Endpoint Interface

placeholder or default values, which the system ﬁlls in when the data is received.

For more information, see the section “Specifying the Data Form and Target”

beginning on page 23-13.

The data types that can be used in the

typelist array are identiﬁed by these

symbols:

'long, 'ulong, 'short, 'byte, 'char, 'unicodechar,

'boolean, 'struct, and 'array. They are described in detail in “Data Type

Symbols” (Table 20-2 on page 20-3) in Newton Programmer’s Reference.

Note that the

'struct and 'array data types are not used alone, but in

conjunction with other elements in a

typelist array. They modify how the other

elements are treated. The

'struct data type deﬁnes the array as an aggregate

structure of various data types that is padded to a long-word boundary (4 bytes in

the Newton system). Note that the whole structure is padded, not each array

element. You must specify the

'struct data type in order to include more than

one type of data in the array.

The

'array data type deﬁnes the array as an aggregate array of one or more

elements of a single data type. The

'array data type is speciﬁed as a NewtonScript

array of three items, like this:

['array, dataTypeSymbol, integer]

Replace the dataTypeSymbol with one of the other simple data types. And integer is

an integer specifying the number of units of that data type to convert. To convert an

entire string, including the terminator, specify zero for

integer. A nonzero value

speciﬁes the exact number of units to be converted, independent of a termination

character in the source string.

Here are some examples of how to use the

'array data type to represent C strings

and Unicode strings in NewtonScript. The ﬁrst example shows how to convert

between a NewtonScript string of undeﬁned length and a C string (translated

to/from Unicode):

['array, 'char, 0]

This example shows how to convert a four-character NewtonScript string to a C string:

['array, 'char, 4]

This example shows how to convert between a NewtonScript string and a

Unicode string:

['array, 'unicodechar, 0]

The 'template data form is intended primarily as a means of communicating

with the lower level communication tools in the Newton system. You can use this

data form to communicate with a remote system, however, you must be careful and

know exactly what you are doing to use it for this purpose. Remember that the

lengths of various data types and the byte order may be different in other systems

and may change in future releases of the Newton operating system.

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