Support reading from the second controller

Signed-off-by: Miquel Sabaté Solà <mssola@mssola.com>

8 files changed, 41 insertions, 41 deletions

diff --git a/.nasm/memory.txt b/.nasm/memory.txt
index dcdef5e..129737f 100644
--- a/.nasm/memory.txt
+++ b/.nasm/memory.txt
@@ -17,8 +17,7 @@ $10: zp_displayed
 $11: zp_timer
 $20: zp_flags
 $21: zp_prev
-$22: zp_buttons1
-$23: zp_buttons2
+$22: zp_buttons
 $24: zp_level
 $25: zp_level_kind
 $26: zp_multiplayer
@@ -66,8 +65,8 @@ $2006: m_address
 $2007: m_data
 $4010: m_dmc
 $4014: m_dma
-$4016: m_joypad1
+$4016: m_joypad
 $4017: m_frame_counter
 
 --- Summary (in bytes) ---
-- Internal RAM: 391/2048 (19.09%)
+- Internal RAM: 390/2048 (19.04%)
diff --git a/.nasm/segments.txt b/.nasm/segments.txt
index e5b18a5..0b837c2 100644
--- a/.nasm/segments.txt
+++ b/.nasm/segments.txt
@@ -1,8 +1,4 @@
 - HEADER: 16/16 (100%)
-<<<<<<< HEAD
-- ROM0: 6609/32762 (20.17%)
-=======
-- ROM0: 6658/32762 (20.32%)
->>>>>>> 823e1f6ed102 (State game over only when all players are dead)
+- ROM0: 6671/32762 (20.36%)
 - ROMV: 6/6 (100%)
 - ROM2: 8192/8192 (100%)
diff --git a/include/joypad.s b/include/joypad.s
index cc15d02..784bb81 100644
--- a/include/joypad.s
+++ b/include/joypad.s
@@ -9,17 +9,18 @@
     BUTTON_LEFT   = 1 << 1
     BUTTON_RIGHT  = 1 << 0
 
-    ;; Port addresses for controllers.
-    m_joypad1 = $4016
-    ;; m_joypad2 = $4017
+    ;; Port address for starting the latch process for both controllers and
+    ;; reading from Joypad 1. The second Joypad can be accessed by reading from
+    ;; $4017, which means that functions down below will simply use an indexed
+    ;; load with the proper value on the index register (i.e. +1).
+    m_joypad = $4016
 
     ;; The previous reading from the latest read controller.
-    zp_prev     = $21
+    zp_prev = $21
 
-    ;; After running a `read_*` function these two variables will contain the
-    ;; given result.
-    zp_buttons1 = $22
-    zp_buttons2 = $23
+    ;; After running a `read_*` function this variable will contain the given
+    ;; result.
+    zp_buttons = $22
 
     ;;;
     ;; Safely read a controller via a re-read algorithm the joypad as indexed by
@@ -35,11 +36,11 @@
         ;; Mario Bros. 3, it should work for us too :P). Otherwise there is the
         ;; algorithm via OAM DMA, but it sure is tricky.
     @reread:
-        lda Joypad::zp_buttons1, x
+        lda Joypad::zp_buttons
         tay
         jsr Joypad::unsafe_read_x
         tya
-        cmp Joypad::zp_buttons1, x
+        cmp Joypad::zp_buttons
         bne @reread
 
         rts
@@ -52,26 +53,26 @@
     .proc unsafe_read_x
         ;; Start the latch process.
         lda #$01
-        sta Joypad::m_joypad1
-        sta Joypad::zp_buttons1, x   ; Bit as a guard for the loop below.
+        sta Joypad::m_joypad
+        sta Joypad::zp_buttons   ; Bit as a guard for the loop below.
         lsr
-        sta Joypad::m_joypad1
+        sta Joypad::m_joypad
 
         ;; Now the joypad is ready to accept reads.
     @loop:
-        lda Joypad::m_joypad1, x
+        lda Joypad::m_joypad, x
         and #%00000011              ; Ignore bits other than controller.
         cmp #$01                    ; Set carry if and only if nonzero.
-        rol Joypad::zp_buttons1, x   ; Carry -> bit 0; bit 7 -> Carry
+        rol Joypad::zp_buttons      ; Carry -> bit 0; bit 7 -> Carry
         bcc @loop
         rts
     .endproc
 .endscope
 
-;; Shortcut for reading the joypad from the first player safely.
-.macro READ_JOYPAD1
-    ldx #$00
-    lda Joypad::zp_buttons1
+;; Shortcut for reading the joypad indexed by 'x' (0 for controller 1; 1 for
+;; controller 2).
+.macro READ_JOYPAD_X
+    lda Joypad::zp_buttons
     sta Joypad::zp_prev
     jsr Joypad::read_x
 .endmacro
diff --git a/src/bullets.s b/src/bullets.s
index 58b6a4a..3cc74b9 100644
--- a/src/bullets.s
+++ b/src/bullets.s
@@ -104,7 +104,7 @@
     @check_bullets_pressed:
         ;; Is the B button pressed? If not go to `@move_bullets` directly.
         lda #(Joypad::BUTTON_B)
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @move_bullets
 
         ;; The B button was pressed. Reset the bullet timer.
diff --git a/src/driver.s b/src/driver.s
index 3bf4399..942bf82 100644
--- a/src/driver.s
+++ b/src/driver.s
@@ -179,7 +179,7 @@
 
         ;; Check if the player is toggling the `pause` state.
         lda #(Joypad::BUTTON_START | Joypad::BUTTON_SELECT)
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @skip_pause_handling
 
         ;; What does the timer say, is the player allowed to do it?
diff --git a/src/jetpac.s b/src/jetpac.s
index 25fdf5a..5fdd01f 100644
--- a/src/jetpac.s
+++ b/src/jetpac.s
@@ -125,8 +125,8 @@
     ;; variables defined before
     sta Globals::zp_flags
     sta Globals::zp_multiplayer
-    sta Joypad::zp_buttons1
-    sta Joypad::zp_buttons2
+    sta Joypad::zp_buttons
+    sta Joypad::zp_prev
     sta Player::zp_state
 
     ;; Initialize the level. We allow the build system to pass its own value for
@@ -187,7 +187,11 @@
     sta PPU::m_mask
 
 @main_game_loop:
-    READ_JOYPAD1
+    ;; Select the joypad from the active player and read it.
+    lda Globals::zp_multiplayer
+    and #$01
+    tax
+    READ_JOYPAD_X
 
     lda Globals::zp_flags
     and #%00000011
diff --git a/src/player.s b/src/player.s
index 53695b4..60005af 100644
--- a/src/player.s
+++ b/src/player.s
@@ -249,7 +249,7 @@
         bit zp_state
         bpl @check_thrust
         lda #Joypad::BUTTON_DOWN
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @check_thrust
         lda #0
         sta zp_velocity_y
@@ -258,7 +258,7 @@
     @check_thrust:
         ;; Check if the player is asking to thrust, otherwise apply gravity.
         lda #(Joypad::BUTTON_UP | Joypad::BUTTON_A)
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @set_gravity
 
         ;; Player is throttling, reflect that on the player's state.
@@ -349,7 +349,7 @@
 
     .proc update_horizontal_position
         lda #Joypad::BUTTON_LEFT
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @check_right
 
         ;; We are facing left, reflect that on the state and the sprite.
@@ -374,7 +374,7 @@
         ;; Same as the part above but applied to going right.
     @check_right:
         lda #Joypad::BUTTON_RIGHT
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @nothing
 
         lda #%01000100
diff --git a/src/title.s b/src/title.s
index 06ca1cb..d091922 100644
--- a/src/title.s
+++ b/src/title.s
@@ -38,7 +38,7 @@
         bne @end
 
         lda #Joypad::BUTTON_UP
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @check_down
 
         lda #SPRITE_Y_POSITION0
@@ -49,7 +49,7 @@
 
     @check_down:
         lda #Joypad::BUTTON_DOWN
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @check_select
 
         lda #SPRITE_Y_POSITION1
@@ -60,13 +60,13 @@
 
     @check_select:
         lda #Joypad::BUTTON_SELECT
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         bne @do_select
 
         ;; If none of the above has been pressed, our only possibility is the
         ;; start button. If that's the case, jump there, otherwise quit.
         lda #(Joypad::BUTTON_START | Joypad::BUTTON_A)
-        and Joypad::zp_buttons1
+        and Joypad::zp_buttons
         beq @end
         JAL start