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Dynamic functions such as printf
Table 2: dinkusr.s Functions
Function name
Function definition
write_char
DINK32 put character to the output buffer.
The simple steps for using these dynamic addresses are:
1. Use DINK32 V11.1 or later.
2. Use #define for local functions that you wish to connect to the DINK32 functions
example: #define printf dink_printf
3. The first executable statement in your C code must be: set_up_transfer_base();
4. Now whenever your program calls one of these functions, such as printf, it will
transfer control to the equivalent DINK32 function.
G.5 Error Conditions.
The only error condition is a trapword exception, which indicates that the
dink_transfer_table address is zero. This is caused by one of the following conditions:
1. The user has not called set_up_transfer_base()
2. R12 is getting trashed before set_up_transfer_base() is called.
3. The DINK32 version does not support dynamic functions. DINK32 V11.0.2 was the
last version that DID NOT support this feature. Ensure that you are using DINK32
V12.0 or greater.
G.6 Alternative method for Metaware only.
While printf is fairly straightforward, scanf is more complex. In the drystone directory, a
local copy of scanf is supplied in the file, support.c. Scanf and printf can also be
emulated in a simpler program when using the metaware compiler. Two metaware
functions are supplied to the user to give control to characters that are scanned into and out
of the program buffers. Refer to the metaware documentation for more information than is
given here.
When the user compiles and links with the -Hsds flag, two functions, int
_putcanon(int a), and int _getcanon() are called whenever the user gets or
receives a character. Thus, the user can write the simple functions shown below, and scanf
and printf will use the DINK32 functions for printf and scanf. In this case, it is not necessary
to use #define to change the name of the printf or scanf functions or write your own printf
or scanf function. It is still necessary to call set_up_transfer_base() as the first
statement in your program.
10G-110
Dink32 R12 User’s Manual