Renesas TM V.3.20A Spezifikationen PDF herunterladen (Seite 236)

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Renesas Technology, Tools FAQs

Last Updated: August 7, 2000

Document Number: 01051080_e

How can I access a bit field with CC32R?

Use one of the following methods to access a bit field.

Access with indirect half-words (see #1 below)1.

Macro Method: using macros for better code efficiency (see #2 below)2.

#1. Accessing bit fields by indirect half-word access method

/* bit field declaration */

typedef union

{

unsigned long Word; /* word data access use */

struct

{

unsigned short dummy7bit :7; /* Extra (fixed to 0) */

unsigned short b8 :1; /* bit No.8 */

unsigned short b7 :1; /* bit No.7 */

unsigned short b6 :1; /* bit No.6 */

unsigned short b5 :1; /* bit No.5 */

unsigned short b4 :1; /* bit No.4 */

unsigned short b3 :1; /* bit No.3 */

unsigned short b2 :1; /* bit No.2 */

unsigned short b1 :1; /* bit No.1 */

unsigned short b0 :1; /* bit No.0 */

} Bit;

} TypeP1;

/* address declaration */

#define io_P1 (*(volatile TypeP1 *)0x00800100)

/* example function for accessing bit field indirectly */

void

foo1()

{

TypeP1 work;

/* write to bit No. 8 */

work.Word = io_P1.Word; /* to read out half-word */

work.Bit.b8 = 0;

io_P1.Word = work.Word; /* to write in half-word */

/* write to bit No. 5 */

work.Word = io_P1.Word; /* to read out half-word */

work.Bit.b5 = 0;

io_P1.Word = work.Word; /* to write in half-word */

}

#2. Using a macro

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