p19a.asm

salloc   ;Struct Allocate
         .block
         lda offset
         sta ptr       ;Set lo addr byte
         bne incoff

         pha
         lda #1        ;Alloc one page
         jsr pgalloc
         tay           ;Page addr -> .Y
         lda #0
         jsr memset    ;Zero the page
         sty page

         lda rootpg
         bne skip
         sty rootpg   ;Assign root ptr
skip     pla

incoff   clc
         adc #entrysize
         sta offset

         lda page
         sta ptr+1     ;Set hi addr byte
         rts

page     .byte 0 ;Current struct page.
offset   .byte 0 ;Current page offset.
         .bend