A166 User's Guide

SOF Assembler Operator

Arguments	SOF operand
Description	The SOF (Segment Offset) operator returns the 16-bit offset of operand from the base address of the 64K segment in which it is defined. SOF may not be applied to group names. The primary use for the SOF operator is loading the peripheral event controller (PEC) source and destination addresses. The PEC unit works with linear addresses and does not use DPP register for memory access. Therefore, the SOF operator must be used to obtain linear addresses. The operand must be the name of a variable, section, special function register (SFR), or register bank. If SOF is used on system names (SFRs), the result is the absolute offset relative to segment 0.
See Also	BOF, POF
Example	1 D100 SECTION DATA 0000 2 V1 DSW 20 0028 0000 R 3 V2 DW SOF V1 ; segment offset of V1 002A 0000 R 4 V3 DW PAG V1 ; page offset of V1 5 D100 ENDS 6 7 DSTP7 EQU 0FDFEh 8 9 C100 SECTION CODE 10 P100 PROC NEAR 0000 E6F80000 R 11 MOV R8,#SOF V1 ; segment offset 0004 F6F8FEFD 12 MOV DSTP7,R8 ; destination for PECC7 0008 E6F50000 R 13 MOV R5,#SOF P100 ; SOF of parent procedure 14 P100 ENDP 15 C100 ENDS 16 END