Sonic 1 prototype collision source code fragment

; https://tcrf.net/Prerelease:Sonic_the_Hedgehog_(Genesis)#Sonic_initial_development_site.Sega_R.26D_news_footage_of_Feb_1990.

    cd_walk equ 0*2

    cd_jump equ 1*2

    cd_up equ 2*2

    cd_down equ 3*2

updotmax equ -4 downdotmax equ 4 jumpdotmax equ 8

sprvo equ $1c
sprho equ $1d
sprvs equ $1e
sprhs equ $1f
------------------------------------------------------------------------
foot colition
col

move.w yposi(a0),d4 move.b sprvo(a0),d1 add.b sprvs(a0),d1 ext.w d1 add.w d1,d4 move.w xposi(a0),d5 move.b sprho(a0),d1 ext.w d1 add.w d1,d5 move.w xspeed(a0),scrhithz ?loop: move.w d4,d2 move.w d5,d3 moveq #0,d0 move.b sprhs(a0),d0 tst.w xspeed(a0) bpl.b ?jump

    btst.b #cd_right,cddot(a0)
    beq.b ?jump

neg.w d0 ?jump: add.w d0,d3 bsr.w scdchk tst.w d1 beq.b ?end bpl.b ?down ?up: cmp.w #updotmax,d1 blt.b ?nomove add.w d1,yposi(a0) ?end: rts ?nomove: bsr.b hoseihsub bra.b ?loop move.w #0,xspeed(a0) rts ?down: move.w d1,d6 swap d6 ?down2: move.w d4,d2 move.w d6,d3 moveq #0,d0 move.b sprhs(a0),d0 tst.w xspeed(a0) bpl.b ?jump3

    btst #cd_left,cddot(a0)
    bne.s ?jump3

neg.w d0 ?jump3: add.w d0,d3 bsr.w scdchk tst.w d1 beq.b ?end2 bpl.b ?down1 ?up2: cmp.w #updotmax,d1 blt.b ?nomove2