Zilog Z8F0130 - Manual (Page 246)

Using the ANSI C-Compiler UM013037-1212
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Zilog Developer Studio II – Z8 Encore!
User Manual
arga: R8, R9
argb: R10, R11, R12, R13
argc: _0_myfunc
argd: _1_myfunc
For a dynamic frame function, the arguments will be on stack. Their offsets from the stack
pointer at the entry point of the assembly function are as follows:
arga: -2
argb: -4
argc: -8
argd: -9
For a dynamic frame function with register parameter passing, some of the arguments will
be in registers and some on stack. Their registers/offsets from the stack pointer at the entry
point of the assembly function are as follows:
arga: R8, R9
argb: R10, R11, R12, R13
argc: -2
argd: -3
Return Values
The assembly function must return the value in the location specified by the C calling con-
vention as described in the
Calling Conventions section on page 215.
For example, if you are using the following C prototype:
long myfunc(short arga, long argb, short *argc)
The assembly function must return the long value in registers R0, R1, R2, and R3.
Preserving Registers
The Z8 Encore! C-Compiler implements a caller save scheme. The caller function pre-
serves the registers, and the called assembly function is not expected to save and restore
any registers that it uses.