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Article #10722

Re: Inversion de bits

#10722
From: J.A. Gutierrez
Date: Thu, 07 Feb 2002 14:11
91 lines
3811 bytes
Fco. Javier Espejo <jespejoYASABES@quehacerarrakis.es> wrote:
: Hay un fallo gordo, con esto se soluciona ;-)
: #define sizeof(unsigned char) (sizeof(unsigned char)*8)

    * hay otro fallo: en realidad deberia ser mas o menos asi:

    for(i=0,d=0,cc=c;i<8*sizeof(unsigned char)-1;i++)
    {
        d |= cc&0x01;
        cc = cc >> 1;
        d = d << 1;
    }
    d |= cc&0x01;

    * Otra opcion:

#define invert_ucb(a) ( \
    i.u.b0 = (a).b7, \
    i.u.b1 = (a).b6, \
    i.u.b2 = (a).b5, \
    i.u.b3 = (a).b4, \
    i.u.b4 = (a).b3, \
    i.u.b5 = (a).b2, \
    i.u.b6 = (a).b1, \
    i.u.b7 = (a).b0, \
    i.c )

typedef struct ucb {
    unsigned char   b0:1,
                    b1:1,
                    b2:1,
                    b3:1,
                    b4:1,
                    b5:1,
                    b6:1,
                    b7:1;
                } ucb;

union {
        ucb u;
        unsigned char c;
    } u,i;

	u.c=c;
	invert_ucb(u.u);



	* La tabla:

static unsigned char ucv[]={
0x00, 0x80, 0x40, 0xc0, 0x20, 0xa0, 0x60, 0xe0,
0x10, 0x90, 0x50, 0xd0, 0x30, 0xb0, 0x70, 0xf0,
0x08, 0x88, 0x48, 0xc8, 0x28, 0xa8, 0x68, 0xe8,
0x18, 0x98, 0x58, 0xd8, 0x38, 0xb8, 0x78, 0xf8,
0x04, 0x84, 0x44, 0xc4, 0x24, 0xa4, 0x64, 0xe4,
0x14, 0x94, 0x54, 0xd4, 0x34, 0xb4, 0x74, 0xf4,
0x0c, 0x8c, 0x4c, 0xcc, 0x2c, 0xac, 0x6c, 0xec,
0x1c, 0x9c, 0x5c, 0xdc, 0x3c, 0xbc, 0x7c, 0xfc,
0x02, 0x82, 0x42, 0xc2, 0x22, 0xa2, 0x62, 0xe2,
0x12, 0x92, 0x52, 0xd2, 0x32, 0xb2, 0x72, 0xf2,
0x0a, 0x8a, 0x4a, 0xca, 0x2a, 0xaa, 0x6a, 0xea,
0x1a, 0x9a, 0x5a, 0xda, 0x3a, 0xba, 0x7a, 0xfa,
0x06, 0x86, 0x46, 0xc6, 0x26, 0xa6, 0x66, 0xe6,
0x16, 0x96, 0x56, 0xd6, 0x36, 0xb6, 0x76, 0xf6,
0x0e, 0x8e, 0x4e, 0xce, 0x2e, 0xae, 0x6e, 0xee,
0x1e, 0x9e, 0x5e, 0xde, 0x3e, 0xbe, 0x7e, 0xfe,
0x01, 0x81, 0x41, 0xc1, 0x21, 0xa1, 0x61, 0xe1,
0x11, 0x91, 0x51, 0xd1, 0x31, 0xb1, 0x71, 0xf1,
0x09, 0x89, 0x49, 0xc9, 0x29, 0xa9, 0x69, 0xe9,
0x19, 0x99, 0x59, 0xd9, 0x39, 0xb9, 0x79, 0xf9,
0x05, 0x85, 0x45, 0xc5, 0x25, 0xa5, 0x65, 0xe5,
0x15, 0x95, 0x55, 0xd5, 0x35, 0xb5, 0x75, 0xf5,
0x0d, 0x8d, 0x4d, 0xcd, 0x2d, 0xad, 0x6d, 0xed,
0x1d, 0x9d, 0x5d, 0xdd, 0x3d, 0xbd, 0x7d, 0xfd,
0x03, 0x83, 0x43, 0xc3, 0x23, 0xa3, 0x63, 0xe3,
0x13, 0x93, 0x53, 0xd3, 0x33, 0xb3, 0x73, 0xf3,
0x0b, 0x8b, 0x4b, 0xcb, 0x2b, 0xab, 0x6b, 0xeb,
0x1b, 0x9b, 0x5b, 0xdb, 0x3b, 0xbb, 0x7b, 0xfb,
0x07, 0x87, 0x47, 0xc7, 0x27, 0xa7, 0x67, 0xe7,
0x17, 0x97, 0x57, 0xd7, 0x37, 0xb7, 0x77, 0xf7,
0x0f, 0x8f, 0x4f, 0xcf, 0x2f, 0xaf, 0x6f, 0xef,
0x1f, 0x9f, 0x5f, 0xdf, 0x3f, 0xbf, 0x7f, 0xff
};


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From: "J.A. Gutierrez" <spd@daphne.cps.unizar.es>
Newsgroups: es.comp.os.linux.programacion
Subject: Re: Inversion de bits
Date: 7 Feb 2002 14:11:42 GMT
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