diff options
| -rw-r--r-- | .nasm/memory.txt | 3 | ||||
| -rw-r--r-- | .nasm/segments.txt | 2 | ||||
| -rw-r--r-- | src/enemies.s | 2 | ||||
| -rw-r--r-- | src/jetpac.s | 1 | ||||
| -rw-r--r-- | src/prng.s | 35 |
5 files changed, 40 insertions, 3 deletions
diff --git a/.nasm/memory.txt b/.nasm/memory.txt index 3603fc9..397a90b 100644 --- a/.nasm/memory.txt +++ b/.nasm/memory.txt @@ -16,6 +16,7 @@ $0E: zp_player_tile_waist $0F: zp_player_tile_bottom $10: zp_displayed $11: zp_timer +$12: zp_last_rand $20: zp_flags $21: zp_prev $22: zp_buttons @@ -80,4 +81,4 @@ $4016: m_joypad $4017: m_frame_counter --- Summary (in bytes) --- -- Internal RAM: 418/2048 (20.41%) +- Internal RAM: 419/2048 (20.46%) diff --git a/.nasm/segments.txt b/.nasm/segments.txt index 2c4877f..85c337d 100644 --- a/.nasm/segments.txt +++ b/.nasm/segments.txt @@ -1,4 +1,4 @@ - HEADER: 16/16 (100%) -- ROM0: 8253/32762 (25.19%) +- ROM0: 8276/32762 (25.26%) - ROMV: 6/6 (100%) - ROM2: 8192/8192 (100%) diff --git a/src/enemies.s b/src/enemies.s index 6201416..2208758 100644 --- a/src/enemies.s +++ b/src/enemies.s @@ -244,7 +244,7 @@ ;; The Y coordinate is also set at random within the bounds of the ;; playable screen. - jsr Prng::random_valid_y_coordinate + jsr Prng::random_non_repeated_valid_y_coordinate ldx Globals::zp_tmp0 inx sta Enemies::zp_pool_base, x diff --git a/src/jetpac.s b/src/jetpac.s index f99c8b0..3cf8f0a 100644 --- a/src/jetpac.s +++ b/src/jetpac.s @@ -130,6 +130,7 @@ sta Joypad::zp_prev sta Player::zp_state sta Items::zp_state + sta Prng::zp_last_rand ;; Initialize the level. We allow the build system to pass its own value for ;; this in `LEVEL`, just in case we want to debug the enemy of a specific @@ -9,6 +9,14 @@ ;; Current random value. Initialized on the title to game transition. zp_rand = $0A + ;; Last random value as stored by + ;; Prng::random_non_repeated_valid_y_coordinate(). + zp_last_rand = $12 + + ;; How many attempts should Prng::random_non_repeated_valid_y_coordinate() + ;; take to find a unique value. + RAND_ATTEMPTS = 3 + ;; Updates the 'a' register with the next random number set after the ;; current value of `zp_rand`, while also making sure that it is a valid ;; screen Y coordinate. @@ -21,6 +29,33 @@ sta zp_rand rts .endproc + + ;; Calls Prng::random_valid_y_coordinate() multiple times until we get a + ;; different value than what we got the last time we called this + ;; function. Realistically this should just take 1 attempt for most cases, + ;; and in the worst case just 2. Nevertheless, we have set a generous value + ;; to 'RAND_ATTEMPTS' just in case. + ;; + ;; NOTE: the 'y' register is preserved. + .proc random_non_repeated_valid_y_coordinate + tya + pha + ldy #RAND_ATTEMPTS + + @again: + jsr Prng::random_valid_y_coordinate + cmp Prng::zp_last_rand + bne @end + dey + bne @again + + @end: + sta Prng::zp_last_rand + pla + tay + lda Prng::zp_last_rand + rts + .endproc .endscope |