This confuses me

00:2A38 3611    ld [hl],$11 <-- 0?,C,B,17
00:2A3A 010000  ld bc,$0000 ---
00:2A3D 21ABCA  ld hl,$CAAB
00:2A40 CB13    rl e
00:2A42 CB12    rl d
00:2A44 35      dec [hl] <-- 0?,C,B,R
00:2A45 281A    jr z,$2A61
00:2A47 CB11    rl c
00:2A49 CB10    rl b <-- BC = 2BC
00:2A4B 2B      dec hl
00:2A4C 2B      dec hl
00:2A4D 79      ld a,c
00:2A4E 96      sub [hl]
00:2A4F 4F      ld c,a
00:2A50 23      inc hl
00:2A51 78      ld a,b
00:2A52 9E      sbc [hl]
00:2A53 47      ld b,a
00:2A54 3008    jr nc,$2A5E
00:2A56 2B      dec hl
00:2A57 79      ld a,c
00:2A58 86      add a,[hl]
00:2A59 4F      ld c,a
00:2A5A 23      inc hl
00:2A5B 78      ld a,b
00:2A5C 8E      adc a,[hl]
00:2A5D 47      ld b,a
00:2A5E 3F      ccf
00:2A5F 18DC    jr $2A3D