minor documentation corrections/clarifications

docs/Enemy Glossary.md

@@ -182,7 +182,7 @@ destroyed.
 ### 03 - Flying Capsule
 
 Other Names: Weapon Zeppelin, Power-Up Capsule, Weapon Wings, Weapon Drop,
-  or Flying Item Pod
+  Flying Item Pod, or Football
 
 Weapon Item transportation device that which travels from the left end of the
 screen to the other in a wave-like pattern.

src/bank0.asm

@@ -345,7 +345,7 @@ set_weapon_item_sprite:
     lsr
     lsr                            ; flash every #$08 frames
     and #$03                       ; keep bits .... ..xx
-    ora #$04                       ; set bit 3
+    ora #$04                       ; set bit 2 (use palette defined in bits 0 and 1)
     sta ENEMY_SPRITE_ATTR,x        ; update enemy sprite attribute so it flashes
 
 @set_sprite_code:
@@ -735,7 +735,7 @@ flying_capsule_routine_01:
 
 ; weapon zeppelin pointer 3
 flying_capsule_routine_02:
-    jmp play_explosion_sound
+    jmp play_explosion_sound ; create explosion sound and 2 sets of explosion type #$89 at location
 
 ; pointer table for rotating gun (#$a * #$2 = #$14 bytes)
 ; level 1 or level 3 enemy

src/bank1.asm

@@ -1430,7 +1430,7 @@ init_pulse_and_noise_channels:
     lda #$00
     tax
 
-; write #$00-#$05 to $0106
+; write #$00 to all sound slots' sound code
 @loop:
     sta SOUND_CODE,x
     inx
@@ -4100,10 +4100,10 @@ load_sprite_to_cpu_mem:
     iny           ; increment sprite_xx read offset
     lda ($08),y   ; load low byte of new sprite read address
     sta $06       ; store low byte into $06
-    iny
+    iny           ; increment sprite_xx read offset
     lda ($08),y   ; load high byte of new sprite read address
     sta $09       ; replace existing read high byte in $09 with new address
-    lda $06       ; load low byte back into $06
+    lda $06       ; load low byte
     sta $08       ; replace existing read low byte in $08 with new address
     ldy #$00      ; clear sprite_xx read offset since starting at new address
 
@@ -4135,7 +4135,7 @@ load_sprite_to_cpu_mem:
     lda ($08),y               ; read 3rd byte (sprite tile attributes) (Byte 2)
     and $0d                   ; keep/strip sprite palette from sprite tile byte 2, based on bit 2 of SPRITE_ATTR
     ora $00                   ; merge sprite code tile byte 2 with attribute data from SPRITE_ATTR
-    eor $0b                   ; exclusive to handle flipping a flipped sprite tile, e.g. flip + flip = no flip
+    eor $0b                   ; exclusive or to handle flipping a flipped sprite tile, e.g. flip + flip = no flip
     sta OAMDMA_CPU_BUFFER+2,x ; write sprite attributes to CPU buffer
     iny                       ; increment sprite_xx read offset
     lda $0b
@@ -4218,7 +4218,7 @@ draw_player_hud_sprites:
     ldy #$04                  ; set hud_sprites base offset to show GAME OVER
     lsr
     bcs @four_sprites         ; branch if in game over
-    ldy $00                   ; not in game over, load number of lives remaining
+    ldy $00                   ; not in game over, load number of lives remaining for current player
     lda P1_NUM_LIVES,y        ; player y lives
     ldy #$00                  ; set hud_sprites base offset to show medals
     cmp #$04
@@ -4240,7 +4240,7 @@ draw_player_hud_sprites:
     lda $00
     sta OAMDMA_CPU_BUFFER+2,x   ; write the tile attributes (blue palette for p1, red palette for p2)
     lsr                         ; set carry flag if on player 2
-    lda sprite_sprite_medal_x_offset,y ; load x offset based on sprite number
+    lda sprite_medal_x_offset,y ; load x offset based on sprite number
     bcc @continue
     adc #$af                    ; add #$af to sprite x offset if on player 2 (see previous lsr)
 
@@ -4263,7 +4263,7 @@ hud_sprites:
     .byte $0a,$0a,$0a,$0a ; medals
     .byte $02,$04,$06,$08 ; game over text
 
-sprite_sprite_medal_x_offset:
+sprite_medal_x_offset:
     .byte $10,$1c,$28,$34
     .byte $10,$1c,$28,$34
 

src/bank7.asm

@@ -341,7 +341,7 @@ remove_registers_from_stack_and_rti:
     pla ; remove byte from stack
     tay ; store in y
     pla ; remove byte from stack
-    tax ; story in x
+    tax ; store in x
     pla ; remove byte stack
     plp ; set cpu flags from stack
 
@@ -2380,7 +2380,7 @@ change_ppu_write_address:
     lda #$01                           ; specifies to increment graphic read address by 1 byte
     ldx #$00                           ; specifies that the 2-byte graphic read address is located at $00
     jsr advance_graphic_read_addr      ; increment 2-byte graphic read address at $00 by 1 byte
-    jmp begin_ppu_graphics_block_write ; start populating nametable with zeros
+    jmp begin_ppu_graphics_block_write ; start writing graphics block to PPU
 
 ; handle when entire graphic data code has been read
 ; restore previously-loaded bank and re-init the PPU
@@ -3905,7 +3905,7 @@ set_frame_scroll_weapon_strength:
 @p2_game_over_status:
     ldy P2_GAME_OVER_STATUS                          ; player 2 game over state (1 = game over)
     bne run_player_invincibility_and_weapon_strength ; branch if player 2 is in game over, or if this is a single player game
-    ora #$02                                         ; set bit 2 to #$01 when player 2 is not in game over
+    ora #$02                                         ; set bit 1 to #$01 when player 2 is not in game over
 
 ; a will be #$00 when both players are in game over
 ; a will be #$01 when player 1 not game over, player 2 game over (or not playing)
@@ -5107,7 +5107,7 @@ apply_gravity:
 
 ; player death
 init_player_dec_num_lives:
-    jsr init_player_and_weapon
+    jsr init_player_and_weapon ; initialize player variables to 0
     sta PLAYER_STATE,x         ; set player state to #$00 (falling into level)
     lda P1_NUM_LIVES,x         ; load player number of lives
     beq @set_game_over         ; branch if no more lives
@@ -5291,6 +5291,9 @@ set_carry_exit:
     sec ; set carry flag
     rts
 
+; initialize player variables to 0
+; input
+;  * x - player offset (0 = p1, 1 = p2)
 init_player_and_weapon:
     lda #$00                ; a = #$00
     sta P1_CURRENT_WEAPON,x ; reset current player's weapon