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Routines |
| Prev: 26011 | Up: Map | Next: 26190 |
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Scrolls the play area horizontally by shifting pixel data left using
RLD instructions.
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| ScrollPlayarea_Left | 26012 | LD HL,(30743) | HL=*Current_ScreenPosition. | |
| 26015 | LD D,H | Copy the screen position pointer into DE. | ||
| 26016 | LD E,L | |||
| 26017 | LD A,(30745) | A=*ScrollPhase_Counter. | ||
| 26020 | LD C,A | Copy the scroll phase counter into C. | ||
| 26021 | INC A | Increment the scroll phase counter by one. | ||
| 26022 | AND %00000111 | Ensure the counter is limited to being a number between 0-7. | ||
| 26024 | LD (30745),A | Write the scroll phase counter back to *ScrollPhase_Counter. | ||
| 26027 | JR NZ,ScrollPlayarea_UpdateColumnPointer | Jump to ScrollPlayarea_UpdateColumnPointer if A is not zero. | ||
| 26029 | INC L | Increment L by one. | ||
| 26030 | JR NZ,ScrollPlayarea_StorePointer | Jump to ScrollPlayarea_StorePointer if L is not zero. | ||
| 26032 | LD A,H | H+=5. | ||
| 26033 | ADD A,5 | |||
| 26035 | LD H,A | |||
| ScrollPlayarea_StorePointer | 26036 | LD (30743),HL | Write HL to *Current_ScreenPosition. | |
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Set up the column data pointer for new graphics data.
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| ScrollPlayarea_UpdateColumnPointer | 26039 | LD A,E | E+=8. | |
| 26040 | ADD A,8 | |||
| 26042 | LD E,A | |||
| 26043 | JR NC,ScrollPlayarea_SetupScroll | Jump to ScrollPlayarea_SetupScroll if {} is higher. | ||
| 26045 | LD A,D | D+=5. | ||
| 26046 | ADD A,5 | |||
| 26048 | LD D,A | |||
| ScrollPlayarea_SetupScroll | 26049 | LD A,C | Load the original scroll phase counter value into A. | |
| 26050 | LD B,1 | Set a counter in B for 1 column to process. | ||
| 26052 | CALL PrepareScrollData | Call PrepareScrollData. | ||
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Start of screen buffer.
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| 26055 | LD HL,16415 | HL=16415 (screen buffer location). | ||
| 26058 | LD D,H | Copy the screen position pointer into DE. | ||
| 26059 | LD E,L | |||
| 26060 | EXX | Switch to the shadow registers. | ||
| ScrollPlayarea_ProcessRows | 26061 | LD A,(DE) | A=*DE. | |
| 26062 | INC E | Increment E by one. | ||
| 26063 | LD L,A | L=A. | ||
| 26064 | LD H,31 | H=31. | ||
| 26066 | ADD HL,HL | Multiply HL by 4. | ||
| 26067 | ADD HL,HL | |||
| 26068 | EXX | Switch to the shadow registers. | ||
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Scroll one character row (32 characters) left by 1 pixel using
RLD.
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| 26069 | LD B,4 | B=4. | ||
| ScrollCharacterRow_Left | 26071 | EXX | Switch to the shadow registers. | |
| 26072 | LD A,(HL) | A=*HL. | ||
| 26073 | INC L | Increment L by one. | ||
| 26074 | EXX | Switch to the shadow registers. | ||
| 26075 | RLD | RLD. | ||
| 26077 | DEC L | Decrease L by one. | ||
| 26078 | RLD | RLD. | ||
| 26080 | DEC L | Decrease L by one. | ||
| 26081 | RLD | RLD. | ||
| 26083 | DEC L | Decrease L by one. | ||
| 26084 | RLD | RLD. | ||
| 26086 | DEC L | Decrease L by one. | ||
| 26087 | RLD | RLD. | ||
| 26089 | DEC L | Decrease L by one. | ||
| 26090 | RLD | RLD. | ||
| 26092 | DEC L | Decrease L by one. | ||
| 26093 | RLD | RLD. | ||
| 26095 | DEC L | Decrease L by one. | ||
| 26096 | RLD | RLD. | ||
| 26098 | DEC L | Decrease L by one. | ||
| 26099 | RLD | RLD. | ||
| 26101 | DEC L | Decrease L by one. | ||
| 26102 | RLD | RLD. | ||
| 26104 | DEC L | Decrease L by one. | ||
| 26105 | RLD | RLD. | ||
| 26107 | DEC L | Decrease L by one. | ||
| 26108 | RLD | RLD. | ||
| 26110 | DEC L | Decrease L by one. | ||
| 26111 | RLD | RLD. | ||
| 26113 | DEC L | Decrease L by one. | ||
| 26114 | RLD | RLD. | ||
| 26116 | DEC L | Decrease L by one. | ||
| 26117 | RLD | RLD. | ||
| 26119 | DEC L | Decrease L by one. | ||
| 26120 | RLD | RLD. | ||
| 26122 | DEC L | Decrease L by one. | ||
| 26123 | RLD | RLD. | ||
| 26125 | DEC L | Decrease L by one. | ||
| 26126 | RLD | RLD. | ||
| 26128 | DEC L | Decrease L by one. | ||
| 26129 | RLD | RLD. | ||
| 26131 | DEC L | Decrease L by one. | ||
| 26132 | RLD | RLD. | ||
| 26134 | DEC L | Decrease L by one. | ||
| 26135 | RLD | RLD. | ||
| 26137 | DEC L | Decrease L by one. | ||
| 26138 | RLD | RLD. | ||
| 26140 | DEC L | Decrease L by one. | ||
| 26141 | RLD | RLD. | ||
| 26143 | DEC L | Decrease L by one. | ||
| 26144 | RLD | RLD. | ||
| 26146 | DEC L | Decrease L by one. | ||
| 26147 | RLD | RLD. | ||
| 26149 | DEC L | Decrease L by one. | ||
| 26150 | RLD | RLD. | ||
| 26152 | DEC L | Decrease L by one. | ||
| 26153 | RLD | RLD. | ||
| 26155 | DEC L | Decrease L by one. | ||
| 26156 | RLD | RLD. | ||
| 26158 | DEC L | Decrease L by one. | ||
| 26159 | RLD | RLD. | ||
| 26161 | DEC L | Decrease L by one. | ||
| 26162 | RLD | RLD. | ||
| 26164 | DEC L | Decrease L by one. | ||
| 26165 | RLD | RLD. | ||
| 26167 | DEC L | Decrease L by one. | ||
| 26168 | RLD | RLD. | ||
| 26170 | LD L,E | L=E. | ||
| 26171 | INC H | Increment H by two. | ||
| 26172 | INC H | |||
| 26173 | DJNZ ScrollCharacterRow_Left | Decrease counter by one and loop back to ScrollCharacterRow_Left until counter is zero. | ||
| 26175 | LD A,32 | Move down one character row. | ||
| 26177 | ADD A,E | |||
| 26178 | LD E,A | |||
| 26179 | LD L,A | Update the screen pointer. | ||
| 26180 | JR NC,ScrollPlayarea_NextRow | Jump to ScrollPlayarea_NextRow if {} is higher. | ||
| 26182 | LD D,72 | D=72. | ||
| ScrollPlayarea_NextRow | 26184 | LD H,D | Update the screen pointer. | |
| 26185 | EXX | Switch to the shadow registers. | ||
| 26186 | DJNZ ScrollPlayarea_ProcessRows | Decrease counter by one and loop back to ScrollPlayarea_ProcessRows until counter is zero. | ||
| 26188 | EXX | Switch back to the normal registers. | ||
| 26189 | RET | Return. | ||
| Prev: 26011 | Up: Map | Next: 26190 |