NODPPSAVE Compiler Directive

Abbreviation

NODS

Arguments

None.

Default

The DPP0 and DPP3 registers are saved on interrupt entries.

µVision

Options — C166 — Save DPP on Interrupt Entry.

Description

The NODPPSAVE directive instructs the compiler not to preserve the DPP0 and DPP3 registers inside interrupt functions. This control is useful when writing applications for the C167 microcontroller using the MOD167 directive. It may be used when you are certain the DPP0 and DPP3 registers are not altered in assembly subroutines and when all C modules are compiled using the MOD167 directive.

Note

The C run-time libraries for the C16x/ST10 microcontroller family do not alter the contents of the DPP0 and DPP3 registers.

See Also

MOD167

Example

C166 SAMPLE.C NODPPSAVE

#pragma NODPPSAVE

The following example:

stmt lvl  source

   1      extern void efunc (void);
   2
   3      void func (void) interrupt 0x21
   4                       using     ireg1
   5      {
   6   1    efunc ();
   7   1  }

demonstrates code generated using the NODPPSAVE directive:

Code Generated
Normally

        ; FUNCTION func (BEGIN)
        ; SOURCE LINE # 3
0000 C6030300      SCXT    DPP3,#03H
0004 CC00          NOP
0006 F6F00000 R    MOV     ireg1,R0
000A C60800C0 R    SCXT    CP,#ireg1
000E CC00          NOP
0010 EC00          PUSH    DPP0
0012 C6871000      SCXT    MDC,#010H
0016 EC06          PUSH    MDH
0018 EC07          PUSH    MDL

        ; SOURCE LINE # 6
001A CA000000 E    CALLA   cc_UC,efunc

        ; SOURCE LINE # 7
001E FC07          POP     MDL
0020 FC06          POP     MDH
0022 FC87          POP     MDC
0024 FC00          POP     DPP0
0026 FC08          POP     CP
0028 FC03          POP     DPP3
002A FB88          RETI
        ; FUNCTION func (END)

CODE SIZE: 44 Bytes

Code Generated
With NODPPSAVE

        ; FUNCTION func (BEGIN)
        ; SOURCE LINE # 3


0000 F6F00000 R    MOV     ireg1,R0
0004 C60800C0 R    SCXT    CP,#ireg1
0008 CC00          NOP

000A C6871000      SCXT    MDC,#010H
000E EC06          PUSH    MDH
0010 EC07          PUSH    MDL

        ; SOURCE LINE # 6
0012 CA000000 E    CALLA   cc_UC,efunc

        ; SOURCE LINE # 7
0016 FC07          POP     MDL
0018 FC06          POP     MDH
001A FC87          POP     MDC

001C FC08          POP     CP

001E FB88          RETI
        ; FUNCTION func (END)

CODE SIZE: 32 Bytes

NODPPSAVE Compiler Directive

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