Screen handling

[britlion]

This is interesting. There's quite a lot of overhead in PLOT, I think - this is fairly unoptimized, still - and appears to be a little buggy. It also doesn't use the screen tables lookup yet. But it's late and I need to go to bed

Code:

SUB plotPoint (x as uByte, y as uByte)
ASM
ld d,(IX+5) ;'X
ld e,(IX+7) ;'Y

    ld a, 191
    sub e    
    ret c    
    ld e, a    
    and a    
    
    rra        
    scf        
    rra        
    and a    
    rra        
    xor e            
    and 248
    xor e
    ld h, a
    ld a, d
    rlca
    rlca
    rlca
    xor e
    and 199
    xor e
    rlca
    rlca
    ld l, a
    
    ld a, d
    and 7
    ld b, a
    inc b
    ld a, 1
    
    plotPoint_loop:
        rrca
    djnz plotPoint_loop    
    ;cpl
    ld b, a    
    ld a, (hl)
    or b    
    ld (hl), a
    
END ASM
END SUB

FUNCTION t() as uLong
asm
    DI
    LD DE,(23674)
    LD D,0
    LD HL,(23672)
    EI
end asm
end function


dim time0, time1, time2 as long
dim n as uInteger

cls

for n=1 to 150
plotPoint(n,n-1)
plot n,n+3
next n


time0=t()
for n=0 to 50000
plot 50,50
next n

time1=t()
for n=0 to 50000
plotPoint(50,50)
next n

time2=t()

print "ZX Basic 50,000 plot:"
print time1-time0;"frames =";(time1-time0)/cast(float,50);" seconds"
print
print "plotPoint 50,000 times:"
print time2-time1;"frames=";(time2-time1)/cast(float,50);" seconds"