A_Times_DE-Crazy Z80

A_Times_DE:
;Input:
;     A,DE
;Outputs:
;     A is 0
;     BC is not changed
;     DE is not changed
;     HL is the result
;     z flag is set
;     c flag is set if the input A is not 0
;Notes:
;           If A is 0, 29 cycles
;Speed: 145+6n+21b cycles
;           n=floor(log(a)/log(2))
;           b is the number of bits in the number
;           Testing over all values of A from 1 to 255:
;           313.7058824 average cycles
;           Worst: 355
;           Best  : 166 (non trivial)
;Size: 25 bytes
     ld hl,0           ;10
     or a \ ret z     ;9
     cpl \ scf        ;8
     adc a,a         ;4
     jp nc,$+7       ;10         ;45
Loop:
     add a,a          ;4
     jp c,$-1         ;10         ;14(7-n)

     add hl,de        ;11         ;11         (the rest are counted below)
     add a,a          ;4           ;4b
     ret z              ;5|11      ;5b+6
     add hl,hl         ;11         ;11b-11
     jp p,$-4         ;21|20     ;20n+b
     jp $-7