Some code snippet for copy bit #2 to bit #1. Can be extended to copy bit #x to bit #x-1

CopyBit2OnBit1

// First (worst) version
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%00000100            // 2by + 2cy
    beq SetBitToZero   // 2by + 2cy
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    ora #%00000010            // 2by + 2cy
    jmp !+                    // 3by + 3cy

  SetBitToZero:
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%11111101            // 2by + 2cy

  !:
    sta c64lib.SPRITE_MSB_X   // 3by + 4cy
                              //23by + 27cy

// Second version
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%00000100            // 2by + 2cy
    lsr                       // 1by + 2cy
    sta temp                  // 3by + 4cy
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%11111101            // 2by + 2cy
    ora temp                  // 3by + 4cy
    sta c64lib.SPRITE_MSB_X   // 3by + 4cy
                              //20by + 26cy

// Second version using ZP vars
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%00000100            // 2by + 2cy
    lsr                       // 1by + 2cy
    sta ZpVar1                // 2by + 3cy
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%11111101            // 2by + 2cy
    ora ZpVar1                // 2by + 3cy
    sta c64lib.SPRITE_MSB_X   // 3by + 4cy
                              //18by + 24cy

// Third version
    lda c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%11111101            // 2by + 2cy
    sta c64lib.SPRITE_MSB_X   // 3by + 4cy
    and #%00000100            // 2by + 2cy
    lsr                       // 1by + 2cy
    ora c64lib.SPRITE_MSB_X   // 3by + 4cy
    sta c64lib.SPRITE_MSB_X   // 3by + 4cy
                              //17by + 22cy