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Change MSB and LSB

Because of Layout I had connected P1.0 to LCD.7, P1.1 to LCD.6 ... P1.7 to LCD.0! Now I have to convert the sending and incoming data. MSB has to become LSB.
Is their a esay way to do this?

Thanks a lot

Parents

0 Dan Henry over 21 years ago

I would be tempted to try something like the following (I can't try it now because I am at a location without access to my Keil toolchain).

static unsigned char bdata src_byte;
static unsigned char bdata dst_byte;

static sbit src_bit0 = src_byte ^ 0;
static sbit src_bit1 = src_byte ^ 1;
static sbit src_bit2 = src_byte ^ 2;
static sbit src_bit3 = src_byte ^ 3;
static sbit src_bit4 = src_byte ^ 4;
static sbit src_bit5 = src_byte ^ 5;
static sbit src_bit6 = src_byte ^ 6;
static sbit src_bit7 = src_byte ^ 7;

static sbit dst_bit0 = dst_byte ^ 0;
static sbit dst_bit1 = dst_byte ^ 1;
static sbit dst_bit2 = dst_byte ^ 2;
static sbit dst_bit3 = dst_byte ^ 3;
static sbit dst_bit4 = dst_byte ^ 4;
static sbit dst_bit5 = dst_byte ^ 5;
static sbit dst_bit6 = dst_byte ^ 6;
static sbit dst_bit7 = dst_byte ^ 7;

unsigned char reverse_bits(unsigned char b)
{
    src_byte = b;

    dst_bit0 = src_bit7;
    dst_bit1 = src_bit6;
    dst_bit2 = src_bit5;
    dst_bit3 = src_bit4;
    dst_bit4 = src_bit3;
    dst_bit5 = src_bit2;
    dst_bit6 = src_bit1;
    dst_bit7 = src_bit0;

    return dst_byte;
}

I wouldn't be surprised if the bit copying boiled down to a sequence of:

    MOV C,src_bit7
    MOV dst_bit0,C
    ; ...

Reply

0 Dan Henry over 21 years ago

I would be tempted to try something like the following (I can't try it now because I am at a location without access to my Keil toolchain).

static unsigned char bdata src_byte;
static unsigned char bdata dst_byte;

static sbit src_bit0 = src_byte ^ 0;
static sbit src_bit1 = src_byte ^ 1;
static sbit src_bit2 = src_byte ^ 2;
static sbit src_bit3 = src_byte ^ 3;
static sbit src_bit4 = src_byte ^ 4;
static sbit src_bit5 = src_byte ^ 5;
static sbit src_bit6 = src_byte ^ 6;
static sbit src_bit7 = src_byte ^ 7;

static sbit dst_bit0 = dst_byte ^ 0;
static sbit dst_bit1 = dst_byte ^ 1;
static sbit dst_bit2 = dst_byte ^ 2;
static sbit dst_bit3 = dst_byte ^ 3;
static sbit dst_bit4 = dst_byte ^ 4;
static sbit dst_bit5 = dst_byte ^ 5;
static sbit dst_bit6 = dst_byte ^ 6;
static sbit dst_bit7 = dst_byte ^ 7;

unsigned char reverse_bits(unsigned char b)
{
    src_byte = b;

    dst_bit0 = src_bit7;
    dst_bit1 = src_bit6;
    dst_bit2 = src_bit5;
    dst_bit3 = src_bit4;
    dst_bit4 = src_bit3;
    dst_bit5 = src_bit2;
    dst_bit6 = src_bit1;
    dst_bit7 = src_bit0;

    return dst_byte;
}

I wouldn't be surprised if the bit copying boiled down to a sequence of:

    MOV C,src_bit7
    MOV dst_bit0,C
    ; ...

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