fast_hclr:
lda HGR_PAGE
sta hclr_smc+2
ldy #0
hclr_outer:
tya
hclr_inner:
hclr_smc:
sta $2000,Y
iny
bne hclr_inner
inc hclr_smc+2
lda hclr_smc+2
and #$1f
bne hclr_outer
rts