horyzontally centered image in CRT
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@ -89,7 +89,7 @@ main:
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; test draw character routine
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; test draw character routine
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call cursor_pos_home
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call cursor_pos_home
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ldi r19, 12
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ldi r19, 14
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dctest:
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dctest:
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ldi r18, 0x21
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ldi r18, 0x21
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draw_chars:
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draw_chars:
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@ -29,7 +29,7 @@
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.equ TIMER_DELAY_30US = 65535 - 690 ; 719 cycles @ 24Mhz (minus overhead)
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.equ TIMER_DELAY_30US = 65535 - 690 ; 719 cycles @ 24Mhz (minus overhead)
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.equ TIMER_DELAY_2US = 65535 - 17 ; 48 cycles @ 24Mhz (minus overhead)
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.equ TIMER_DELAY_2US = 65535 - 17 ; 48 cycles @ 24Mhz (minus overhead)
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.equ BACK_PORCH_DELAY = 258 ; 186 cycles back porch + 72 cycles to leave 3 chunks empty (image padding)
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.equ BACK_PORCH_DELAY = 234 ; 186 cycles back porch + 48 cycles to leave 2 chunks empty (image padding)
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; ********* FUNCTIONS CALLED BY INTERRUPT ***********
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; ********* FUNCTIONS CALLED BY INTERRUPT ***********
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@ -1350,7 +1350,7 @@ draw_line:
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; chunk 47, 48, 49 (blank)
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; chunk 47, 48, 49 (blank)
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clr A ; 1 cycle
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clr A ; 1 cycle
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out VIDEO_PORT_OUT, A ; 1 cycle
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out VIDEO_PORT_OUT, A ; 1 cycle
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ldi VG_HIGH_ACCUM, 23 ; 1 cycle
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ldi VG_HIGH_ACCUM, 31 ; 1 cycle
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eol_porch_loop: ; requires 3 cpu cycles
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eol_porch_loop: ; requires 3 cpu cycles
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dec VG_HIGH_ACCUM ; 1 cycle
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dec VG_HIGH_ACCUM ; 1 cycle
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brne eol_porch_loop ; 2 if jumps, 1 if continues
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brne eol_porch_loop ; 2 if jumps, 1 if continues
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