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如下面PIC16F1933为例。4 D$ E/ j6 b' e
. I' Q# c' s: f: R+ l% k7 `// Register: LCDPS
2 ^# J% \# Q2 o8 F8 l// LCD Phase Register
$ v* ~" j1 I! L$ |9 w( x8 x8 gvolatile unsigned char LCDPS @ 0x792;0 {: u& e3 Q+ e% s
// bit and bitfield definitions
0 K. r6 d& \ N: Y' h: ~// LCD Prescaler Selection bits
. J4 ?, K, ~% Gvolatile bit LP0 @ ((unsigned)&LCDPS*8)+0;2 i' s) ~) c& n. A m. j
// LCD Prescaler Selection bits
' Y1 p- S9 f- K3 q' }" _volatile bit LP1 @ ((unsigned)&LCDPS*8)+1;7 _6 F5 F8 e& }1 [0 O
// LCD Prescaler Selection bits
+ h$ D% G# z" Q" O( F$ f/ Zvolatile bit LP2 @ ((unsigned)&LCDPS*8)+2;
8 Y; c. j+ k8 y f. a2 V* X" A# c! l// LCD Prescaler Selection bits
4 x: M. ?* s) j1 T- Lvolatile bit LP3 @ ((unsigned)&LCDPS*8)+3;& r! q3 v& a7 ^5 ^
// Write Allow bit
1 t/ A/ p: c1 ~. M: D0 Z! Wvolatile bit WA @ ((unsigned)&LCDPS*8)+4;' V1 [1 k' _! S, q
// LCD Active bit
( h0 }: h' i- m, ~4 a* {volatile bit LCDA @ ((unsigned)&LCDPS*8)+5;
6 i2 ]/ Q2 [9 v/ O// Bias Mode Selection bit1 ^* y2 b! q5 t- y) k: c
volatile bit BIASMD @ ((unsigned)&LCDPS*8)+6;
3 B( l2 z9 o6 t4 u$ G" w// Waveform Type bit
+ z9 |3 |/ C; C8 cvolatile bit WFT @ ((unsigned)&LCDPS*8)+7;
9 {! K; Z% v% I8 |. |" O9 ^9 P ^#ifndef _LIB_BUILD
6 L2 I4 u E6 Wvolatile union {
4 c# U4 x& h* Z. u/ p, | struct {
: u3 G- q5 S, v/ q unsigned LP0 : 1;5 m; F% ]" c, ?( U/ O1 h
unsigned LP1 : 1;& S' i5 H& v, d% s' W
unsigned LP2 : 1;% G# Z" d, p; }% h+ x( p
unsigned LP3 : 1;
" m( t; k c9 }4 }5 E unsigned WA : 1;1 I/ V, {0 y) _9 s; t! T/ t
unsigned LCDA : 1;
* D1 n Y% C- F* P% Y unsigned BIASMD : 1;
3 q8 A+ U. y, r9 ?1 k7 E unsigned WFT : 1;
+ \/ m, K7 w) h6 {' r) l! R };+ C4 _$ Y4 K0 ?
struct {( J' q) O0 } @' B. p) v
unsigned LP : 4;
) E9 p) P& O3 D' G) Z7 q% t: g };: v4 B+ w2 E* N" K) i! G' V/ A
} LCDPSbits @ 0x792;& l2 {& I8 }. k- F
#endif @$ l- N6 Y1 y. A2 `1 Y0 ^
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疑问:
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r( g$ }/ z3 k a6 Q8 Q8 avolatile bit LP0 @ ((unsigned)&LCDPS*8)+0;/ d$ t% l0 b& j& u) A1 w! J
这里的 @是什么用法 ?
$ G' J+ ]4 M3 X' _0 K2,! u( R& W. u& }2 n, V
volatile union {- \ P( u N7 U; w) l4 B4 f: g
struct {+ r9 R* d7 t( V6 j7 D+ w/ ]" `! r
unsigned LP0 : 1;
! o/ C% c* ^- r1 L8 q" |9 t& }. G& s7 r1 Z5 q) J& m9 J: d
这里定义一个union包含struct,但是struct里头又指定 LP0为 unsigned类型,但是前面是 bit型。这个怎么理解 ?7 \! l% A* J9 q5 L
3, ?; X! R5 r6 ?9 e2 v* u
还有LP0 :1 ; 是什么意思呢 ?
' F+ n$ Z; U: Y0 _% q# A5 O- M& t! k: v4 ]$ N- l. L' T
求指教 ? |
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