diff options
| author | Alexey 'Cluster' Avdyukhin <clusterrr@clusterrr.com> | 2020-09-21 00:12:41 +0300 |
|---|---|---|
| committer | Alexey 'Cluster' Avdyukhin <clusterrr@clusterrr.com> | 2020-09-21 00:12:41 +0300 |
| commit | 6d1a15a8ad99725f5e3f9d95b30df53d6a434062 (patch) | |
| tree | 69c9ad7bbd5761315ec23339cf5facedc300a60f /video.asm | |
| parent | 65f7185ad6e99eab403e9111b12e4c34db54136b (diff) | |
More build info
Diffstat (limited to 'video.asm')
| -rw-r--r-- | video.asm | 76 |
1 files changed, 76 insertions, 0 deletions
@@ -13,6 +13,8 @@ LAST_LINE_GAME .rs 2 SCROLL_FINE .rs 1 ; fine scroll position SCROLL_LINES_TARGET .rs 2 ; scrolling target STAR_SPAWN_TIMER .rs 1 ; stars spawn timer + ; for build info +CHR_RAM_SIZE .rs 1 ; CHR RAM size 8*2^xKB ; constants CHARS_PER_LINE .equ 32 @@ -913,3 +915,77 @@ saving_warning_hide: jsr waitblank_simple jsr clear_screen rts + +detect_chr_ram_size: + ; disable PPU + lda #%00000000 + sta $2000 + sta $2001 + jsr waitblank_simple + jsr enable_chr_write + lda #$00 + sta $2006 + sta $2006 + ; store $AA to zero bank + sta <CHR_RAM_SIZE + lda #$AA + sta $2007 + ; calculate bank number +.next_size: + lda #1 + ldx CHR_RAM_SIZE + ; shift 1 to the left CHR_RAM_SIZE times +.shift_loop: + dex + bmi .shift_done + asl A + beq .end ; overflow check + jmp .shift_loop +.shift_done: + ; select this bank + jsr select_chr_bank + ; store $AA + ldx #$00 + stx $2006 + stx $2006 + lda #$AA + sta $2007 + ; check for $AA + stx $2006 + stx $2006 + ldy $2007 ; dump read + cmp $2007 + bne .end ; check failed + ; store $55 + stx $2006 + stx $2006 + lda #$55 + ; check for $55 + sta $2007 + stx $2006 + stx $2006 + ldy $2007 ; dump read + cmp $2007 + bne .end ; check failed + ; select zero bank + lda #0 + jsr select_chr_bank + ; check that $AA is not overwrited + stx $2006 + stx $2006 + lda #$AA + ldy $2007 ; dump read + cmp $2007 + bne .end ; check failed + ; OK! Let's check next bank + inc <CHR_RAM_SIZE + jmp .next_size +.end: + lda #0 + jsr select_chr_bank + lda #0 + sta $2006 + sta $2006 + sta $2007 + jsr disable_chr_write + rts |