(C) S. Medvedev, g.Uglich
I would like to offer readers
"Revue," a procedure of drawing the line, the algorithm is
slightly different from the algorithm procedure of "elementary
graphs. 140.
; Draw subroutine
; At the entrance: BC - coordinates of the beginning; la line
(B = Y, C = X) ; DE - coordinates of the end
; Line (D = Y, E = X)
DRAW EXX
LD BC, # 1C14
EXX
LD A, B
CP D
JR NC, NO_EXX
LD B, D
LD D, A
LD A, C
LD C, E
LD E, A
NO_EXX LD A, C
SUB E
JR NC, X_POSIT
NEG
EXX
LD B, # 1D
EXX
X_POSIT LD L, A
; Offset X
LD A, B
SUB D
; A - the Y offset
CP L
LD H, L
LD B, L
LD HX, B
LD LX, A
JR C, DONE
EXX
LD C, B
LD B, # 14
EXX
LD H, A
LD B, A
LD HX, A
LD A, L
LD LX, A
DONE INC H
INC LX
EXX
LD A, B
LD (COMM), A
LD A, C
LD (COMM1), A
EXX
NEXT PUSH HL
PUSH DE
PUSH BC
CALL PLOT
; 'PLOT' - any procedure your mouth Novki point and the
coordinates in the DE: ; D-Y, E-X. Recommend the procedure
; A. Astafieva.
POP BC
POP DE
POP HL
COMM INC E; *
LD A, HX
SUB LX
LD HX, A
JR C, CARRY
COUNT DEC H
JR NZ, NEXT
RET
CARRY ADD A, B
LD HX, A
COMM1 INC D; *
JR COUNT2
* - These commands can be
replaced by others, so here
You can simply write NOP.
As can be seen, the program uses half Register IX, and
owners assemblers, not digesting "mnemonics LX / HX / LY /
HY, could write:
140.
instead of LD LX, A - DEFB # DD
LD L, A
instead of LD C, HX - DEFB # DD
LD C, H
and t.d.2
To clear conscience say
that the program was written "in
explanation "procedures from the demo" VIBRATIONS ".
*
