unsigned char Byte, i, Bit[8];
for(i=0; i< 8; ++i)
  Bit[i]= (Byte >> i) & 0x01;

unsigned char T;
T= Byte;
.............
// Вывод очередного бита
Out= T & 0x01;
T>>= 1;
............

for (i=0;i<8;++i) {
PORTW.Y=byte&(1<<i);  //W-порт, Y-номер пина
delay_ms(x); //x-нужная задержка
                           };

#define BIT 1 /* задаем нужный номер пина (0...7) */
for (i=0;i<8;++i) {
(byte&(1<<i))? PORTW|=(1<<BIT):PORTW&=~(1<<BIT);
delay_ms(x);
                           };

// value - значение

unsigned char i = 8;

do {

// if(value & 1) PORTW |= (1<<BIT);  // LSB first
// else PORTW &= ~(1<<BIT); // LSB first
// value >>= 1; // LSB first

if(value & 0x80) PORTW |= (1<<BIT); // MSB first
else PORTW &= ~(1<<BIT); // MSB first
value <<= 1; // MSB first

} while(--i);

for(i=0;i<8;i++)
{
  if (InByte & 0x01)
    {PortX.Y=1;InByte=((InByte>>1) | 0x80);}
    else
    {PortX.Y=0;InByte=((InByte>>1) & 0x7F);}
delay_ms(x);
} // сдвиг вправо

for(i=0;i<8;i++)
{
  if (InByte & 0x80)
    {PortX.Y=1;InByte=((InByte<<1) | 0x01);}
    else
    {PortX.Y=0;InByte=((InByte<<1) & 0xFE);}
delay_ms(x);
} // сдвиг влево

#define BIT 1 /* задаем нужный номер пина (0...7) */
for (unsigned char bitmask = 1; bitmask; bitmask <<= 1)
{
   (byte & bitmask)? PORTW |= (1<<BIT): PORTW &= ~(1<<BIT);
   delay_ms(x);
}

(byte & bitmask)? PORTW |= (1<<BIT): PORTW &= ~(1<<BIT);

for (unsigned char mask ...)

...
#define BIT 0
#define PORTW PORTD
#define x 10
...
void transmit_byte(unsigned char const *byte, unsigned char direct){
   unsigned char  mask;
         switch(direct){
        case 0: //младший бит вперед
          for (mask=1;mask;mask<<=1) {PORTW=(*byte&mask)? PORTW|(1<<BIT):PORTW&~(1<<BIT);
                                      delay_us(x); /*или delay_ms(x); */}
         break;
                   case 1:  //старший бит вперед
          for (mask=0x80;mask;mask>>=1) {PORTW=(*byte&mask)? PORTW|(1<<BIT):PORTW&~(1<<BIT);
                                      delay_us(x);}
          
         break;
        
                           }
                                                                                            
                                                                                           }
...
transmit_byte(&byte,0); //младший бит вперед
...
transmit_byte(&byte,1); //старший бит вперед
...

main.cpp:
#include <avr/io.h>
#include <stdint.h>
#define BIT 1
void Test1(uint8_t byte, uint8_t bitmask)
{
(byte & bitmask)? PORTD |= (1<<BIT): PORTD &= ~(1<<BIT);
}

main.lst:
484 .section .text._Z5Test1hh,"ax",@progbits
485 .global _Z5Test1hh
487 _Z5Test1hh:
488 .LFB37:
489 .LSM75:
490 /* prologue: frame size=0 */
491 /* prologue end (size=0) */
492 .LVL9:
493 .LSM76:
494 0000 70E0 ldi r23,lo8(0) ; bitmask,
495 .LVL10:
496 0002 90E0 ldi r25,lo8(0) ; byte,
497 .LVL11:
498 0004 6823 and r22,r24 ; bitmask, byte
499 0006 7923 and r23,r25 ; bitmask, byte
500 .LVL12:
501 0008 672B or r22,r23 ; bitmask
502 000a 01F0 breq .L57 ; ,
503 .LSM77:
504 000c 919A sbi 50-0x20,1 ; ,
505 000e 0895 ret
506 .L57:
507 0010 9198 cbi 50-0x20,1 ; ,
508 0012 0895 ret
509 /* epilogue: frame size=0 */
510 /* epilogue: noreturn */
511 /* epilogue end (size=0) */
512 /* function void Test1(uint8_t, uint8_t) size 10 (10) */

#define PORTW PORTD

void Test1(uchar byte, uchar bitmask)
{
PORTD=(byte & bitmask)? PORTD | (1<<BIT): PORTD & ~(1<<BIT);
}

for ((Direction)? mask=1<<0:mask=1<<7;mask;(Direction)? mask<<=1:mask>>1)
{PORTx=(*byte&mask)? PORTx|(1<<BIT):PORTx&~(1<<BIT);delay_us(x);}

#include    <avr/io.h>
typedef unsigned char uchar;
#define BIT 0
void Test1(uchar byte, uchar bitmask)
{
    (byte & bitmask)? PORTD | (1<<BIT): PORTD & ~(1<<BIT);
}

avr-gcc  -mmcu=atmega8 -Wall -gdwarf-2  -DF_CPU=3686400UL  -Os  -fsigned-char -funsigned-bitfields -fpack-struct -fshort-enums -MD -MP -MT ./release/obj/test.o -MF ./release/dep/test.o.d  -ffunction-sections  -fdata-sections -fverbose-asm -Wa,-ahlmsdc=./release/lst/test.lst -c  test.c -o release/obj/test.o

for([первая инструкция];[условие выполнения];[инструкция после тела]) [тело]

[первая инструкция]
while ([условие выполнения])
{
[тело]
[инструкция после тела]
}

(Direction)? mask=1<<0:mask=1<<7;
while(mask)
  {
   PORTx=(*byte&mask)? PORTx|(1<<BIT):PORTx&~(1<<BIT);
   delay_us(x);
   (Direction)? mask<<=1:mask>>1)
  }

mask=1<<(Direction) ? 0 : 7;
do
{
   *byte & mask ? PORTx |= (1<<BIT) : PORTx &= ~(1<<BIT);
   delay_us(x);
}
while ( Direction ? mask<<=1 : mask>>1 );

void transmit_byte(unsigned char const *byte, unsigned char direct){
   unsigned char  mask;
       for (mask=(direct)? 1:0x80;mask;delay_us(x),mask=(direct)? mask<<1:mask>>1)
                    PORTW=(*byte&mask)? PORTW|(1<<BIT):PORTW&~(1<<BIT);
                                                                                                     }

PORTD=(byte & bitmask)? PORTD | (1<<BIT): PORTD & ~(1<<BIT);

void transmit_byte(unsigned char const *byte, unsigned char direct){
   unsigned char  mask;
       for (mask=(direct)? 1:0x80;mask;mask=(direct)? mask<<1:mask>>1)
                  {PORTW=(*byte&mask)? PORTW|(1<<BIT):PORTW&~(1<<BIT);delay_us(x);}
                                                                 }

(*byte&mask)? (PORTW|=(1<<BIT)):(PORTW&=~(1<<BIT));