3) ZX REVIEW has been the procedure of division
badly non-optimal (I have a suspicion
that the one who sent it just copied it
from the book on what a i-8085, not
using additional commands Z-80).
In DE - dividend, in C - divider
result in HL, the remainder in A.
; DIVIDE DE / C = HL
ORG 40000
ENT
LD DE, 768
LD C, 3
CALL DIV
RET
DIV LD B, 16
LD HL, 0
LD A, H
DV1 RL E
RL D
RLA
SUB C
JR NC, DV2
ADD A, C
DV2 CCF
RL L
RL H
DJNZ DV1
RET
4) The point from the same place, at 1.51 times
faster and at less bytes.
Multiplicand-D
factor - E
result - DE
; MULTIPLY DxE = DE; 0 <= result <65535
ORG 40000
ENT
LD DE, # FEFF
CALL MULT
RET
MULT XOR A
LD B, 8
MU1 RRA
RR E
JR NC, MU0
ADD A, D
MU0 DJNZ MU1
RRA
RR E
LD D, A
RET
