diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/background.s | 6 | ||||
| -rw-r--r-- | src/prng.s | 56 |
2 files changed, 24 insertions, 38 deletions
diff --git a/src/background.s b/src/background.s index a9dfbaf..0facde6 100644 --- a/src/background.s +++ b/src/background.s @@ -3,9 +3,15 @@ .scope Background ;; Screen coordinate on the Y axis where elements can begin to appear (e.g. ;; upper bound for new enemies, starting point for falling items, etc.). + ;; + ;; NOTE: if you change this value, you should re-generate the random values + ;; from prng.s as well. UPPER_MARGIN_Y_COORD = $1A ;; Screen coordinates on the Y axis for the ground. + ;; + ;; NOTE: if you change this value, you should re-generate the random values + ;; from prng.s as well. GROUND_Y_COORD = $C8 ;; Returns whether the given tile position collides with a background @@ -15,48 +15,28 @@ .proc random_valid_y_coordinate ;; Get the new random number and store it right away. ldx zp_rand - lda rand_table, x + lda valid_y_rand_table, x sta zp_rand - - ;; Is this value below ground? - cmp #(Background::GROUND_Y_COORD - 16) - bcc @check_sky - - ;; Yes! Return something that is at least above it. - sec - sbc #(Background::GROUND_Y_COORD - 16) - rts - - @check_sky: - ;; Is this value above the upper screen margin? - cmp #Background::UPPER_MARGIN_Y_COORD - bcs @end - - ;; Yes! Return something that is at least below it. - clc - adc #Background::UPPER_MARGIN_Y_COORD - - @end: rts .endproc .endscope ;; The pre-computed table. -rand_table: - .byte $D7, $3A, $1C, $8F, $09, $B2, $E6, $54, $A3, $91, $2B, $F5, $78, $0D, $4C, $6E - .byte $FF, $C0, $52, $33, $6A, $E9, $9B, $1A, $47, $88, $7D, $21, $0E, $F4, $B3, $9C - .byte $15, $67, $A8, $41, $D2, $39, $80, $76, $C9, $E5, $0A, $1B, $5F, $22, $73, $DA - .byte $B4, $96, $3C, $E0, $8D, $F7, $2A, $05, $9E, $43, $11, $6D, $A7, $58, $C1, $32 - .byte $28, $0F, $79, $BE, $51, $64, $9D, $A9, $3B, $71, $8E, $C6, $4A, $13, $F0, $27 - .byte $E2, $5C, $06, $D3, $95, $B8, $4F, $70, $19, $A4, $6B, $38, $82, $C7, $5E, $01 - .byte $F3, $2D, $9A, $65, $7C, $D1, $0B, $E8, $57, $36, $84, $1F, $B0, $92, $45, $AC - .byte $60, $7E, $A1, $53, $C8, $29, $D4, $FB, $07, $42, $E3, $99, $16, $8A, $3D, $C5 - .byte $24, $B1, $6F, $03, $7A, $E7, $8C, $59, $D0, $46, $93, $1E, $A5, $2C, $B7, $F1 - .byte $89, $55, $C3, $30, $62, $98, $04, $D6, $7F, $A0, $E4, $12, $3B, $81, $F9, $23 - .byte $C4, $0D, $5A, $71, $9F, $B6, $2E, $85, $37, $A9, $18, $6C, $E1, $4B, $D9, $02 - .byte $F8, $63, $B5, $40, $97, $0C, $7A, $51, $A2, $3E, $8F, $D5, $14, $69, $E0, $B8 - .byte $4D, $77, $25, $9B, $0A, $F2, $3C, $86, $E9, $1F, $68, $A3, $50, $C1, $7D, $04 - .byte $B2, $8E, $56, $1D, $73, $9C, $F5, $2A, $61, $D7, $09, $3E, $84, $A0, $E6, $1B - .byte $3F, $C8, $94, $05, $72, $D6, $A7, $4C, $1A, $5F, $B3, $29, $80, $E1, $6D, $9E - .byte $0C, $43, $F7, $8B, $52, $16, $A8, $3D, $91, $2B, $E5, $70, $C6, $4A, $D9, $F8 +valid_y_rand_table: + .byte $25, $87, $B7, $6A, $23, $77, $6D, $71, $6D, $B6, $86, $93, $2B, $97, $A8, $39 + .byte $26, $AE, $A6, $70, $9F, $2D, $74, $B2, $8E, $A5, $33, $3E, $6D, $75, $91, $6B + .byte $A1, $2E, $A4, $7C, $53, $28, $1E, $79, $1B, $6B, $A9, $7E, $76, $74, $90, $B3 + .byte $26, $9B, $2C, $94, $9C, $86, $7A, $B7, $1D, $B4, $72, $82, $7C, $23, $33, $78 + .byte $B0, $70, $B5, $A9, $1B, $70, $83, $28, $73, $24, $7E, $28, $B1, $8A, $75, $9B + .byte $20, $26, $22, $8D, $7C, $3F, $29, $3D, $1F, $72, $22, $A4, $86, $34, $6F, $9C + .byte $20, $A9, $3A, $77, $39, $6F, $3B, $86, $95, $3D, $96, $9F, $56, $84, $53, $77 + .byte $B2, $23, $72, $1C, $99, $B4, $B8, $32, $8E, $A3, $21, $20, $25, $97, $92, $2C + .byte $3E, $96, $B5, $28, $84, $7E, $A7, $8A, $A3, $3E, $A4, $72, $A7, $A8, $6D, $A3 + .byte $AE, $7E, $23, $6E, $6A, $72, $35, $3C, $99, $B3, $37, $22, $7F, $79, $1C, $97 + .byte $52, $77, $77, $95, $B4, $7F, $2D, $28, $71, $9E, $76, $9A, $A0, $32, $23, $7F + .byte $94, $9F, $90, $3C, $AF, $A7, $9C, $B5, $87, $9A, $9E, $84, $B0, $AD, $7D, $9D + .byte $A2, $24, $89, $6A, $79, $81, $A2, $1E, $A9, $1E, $AB, $8D, $6E, $54, $90, $AE + .byte $A4, $B5, $1E, $B4, $53, $9D, $7D, $78, $74, $AD, $6A, $96, $2F, $6F, $29, $9F + .byte $98, $1D, $3B, $57, $6D, $B0, $1C, $88, $B0, $55, $99, $8F, $B1, $3F, $AD, $23 + .byte $92, $7A, $26, $55, $A3, $75, $34, $23, $20, $79, $B0, $A6, $B6, $2A, $20, $8C |