[4f508e6] | 1 | | ------------------------------------------------------------------------------
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| 2 | | vvputsv.s -- output characters to a 4-bit / pixel graphics window
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| 3 | | with variable vertical pitch
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| 4 | | Version 1 -- 1988-10-07 -- D.N. Lynx Crowe
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| 5 | | (c) Copyright 1988 -- D.N. Lynx Crowe
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| 6 | | ------------------------------------------------------------------------------
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| 7 |
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| 8 | | vvputsv(obase, nw, fg, bg, row, col, str, pitch, ht, cgtab)
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| 9 | | uint |obase, nw, fg, bg, row, col, pitch, ht, cgtab[][256];
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| 10 | | char |str;
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| 11 |
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| 12 | | Outputs characters from the string at 'str' to an 'nw'
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| 13 | | character wide 4-bit per pixel graphics window at 'obase'
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| 14 | | at ('row','col'), using 'fg' as the foreground color, and
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| 15 | | 'bg' as the background color. Uses cgtab[][256] as the
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| 16 | | VSDD formatted character generator table. Assumes 'ht' line
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| 17 | | high characters in the cg table. Uses 'pitch' as the vertical
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| 18 | | spacing between character rows. No error checks are done.
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| 19 | | The string must fit the output area (no overlaps, single line).
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| 20 |
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| 21 | | ------------------------------------------------------------------------------
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[f40a309] | 22 | .text
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[4f508e6] | 23 |
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[f40a309] | 24 | .xdef _vvputsv
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[4f508e6] | 25 |
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| 26 | | Argument offsets from a6:
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| 27 |
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| 28 | OBASE = 8 | LONG - Output area base address
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| 29 | NW = 12 | WORD - Character width of output area
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| 30 | FG = 14 | WORD - Foreground color
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| 31 | BG = 16 | WORD - Background color
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| 32 | ROW = 18 | WORD - Row
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| 33 | COL = 20 | WORD - Column
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| 34 | STR = 22 | LONG - String base address
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| 35 | PITCH = 26 | WORD - Vertical spacing between rows
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| 36 | HT = 28 | WORD - Character height (LE PITCH)
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| 37 | CGTAB = 30 | LONG - Character generator table
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| 38 |
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| 39 | | Program constant definitions:
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| 40 |
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| 41 | HPIX = 8 | Character width in pixels
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| 42 | HCW = 4 | Horizontal character width (bytes)
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| 43 | PSHIFT = 12 | Pixel shift into MS bits
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| 44 | HSHIFT = 4 | Pixel right shift
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| 45 |
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[f40a309] | 46 | .page
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[4f508e6] | 47 |
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| 48 | | Register usage:
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| 49 |
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| 50 | | d0 output word and scratch
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| 51 | | d1 CG word and scratch
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| 52 | | d2 pixel counter
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| 53 |
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| 54 | | d3 foreground color (in the 4 ms bits)
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| 55 | | d4 background color (in the 4 ms bits)
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| 56 | | d5 width of the area in bytes
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| 57 | | d6 scan line counter
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| 58 |
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| 59 | | a0 CG table pointer
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| 60 | | a1 output area scan line pointer
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| 61 | | a2 input string character pointer
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| 62 |
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| 63 | | a3 output area character base pointer
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| 64 |
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| 65 | | a6 frame pointer
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| 66 | | a7 stack pointer
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| 67 |
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[f40a309] | 68 | .page
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[4f508e6] | 69 |
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| 70 | _vvputsv: link a6,#0 | Link stack frames
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| 71 | movem.l d3-d6/a3,-(a7) | Save registers we use
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| 72 | move.w #PSHIFT,d1 | Set shift constant
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| 73 | move.w FG(a6),d3 | Setup foreground color
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| 74 | lsl.w d1,d3 | ... in ms 4 bits of d3.W
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| 75 | move.w BG(a6),d4 | Setup background color
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| 76 | lsl.w d1,d4 | ... in ms 4 bits of d4.W
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| 77 | move.w NW(a6),d5 | Get line width in d5.W
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| 78 | lsl.w #2,d5 | Multiply width by 4 for offset
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| 79 | move.w ROW(a6),d0 | Calculate output address
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| 80 | move.w PITCH(a6),d1 | ... PITCH
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| 81 | mulu d1,d0 | ... | ROW
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| 82 | add.w HT(a6),d0 | ... + HT-1
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| 83 | subq.w #1,d0 | ...
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| 84 | mulu d5,d0 | ... | NW
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| 85 | clr.l d1 | ...
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| 86 | move.w COL(a6),d1 | ... +
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| 87 | lsl.w #2,d1 | ... COL | 4
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| 88 | add.l d1,d0 | ...
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| 89 | add.l OBASE(a6),d0 | ... + OBASE
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| 90 | movea.l d0,a3 | Leave output address in a3
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| 91 | movea.l STR(a6),a2 | Put string address in a2
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| 92 |
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| 93 | cgl0: clr.l d0 | Clear out upper bits of d0
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| 94 | move.b (a2)+,d0 | Get next character
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| 95 | beq cgl5 | Done if character EQ 0
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| 96 |
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| 97 | movea.l a3,a1 | Establish output pointer in a1
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| 98 | adda.l #HCW,a3 | Update output pointer for next char.
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| 99 | movea.l CGTAB(a6),a0 | Establish CG pointer in a0
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| 100 | lsl.w #1,d0 | ... 2 | character
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| 101 | adda.w d0,a0 | ... + cg table address
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| 102 | move.w HT(a6),d6 | Set scan line counter in d6
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| 103 | subq.w #1,d6 | ... to HT-1
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| 104 |
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[f40a309] | 105 | .page
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[4f508e6] | 106 | cgl1: move.w (a0),d1 | Get character generator word in d1
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| 107 | move.w #(HPIX/2)-1,d2 | Set pixel counter in d2
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| 108 |
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| 109 | cgl2: lsr.w #HSHIFT,d0 | Shift output word right 1 pixel
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| 110 | btst.l #0,d1 | Check CG word ls bit
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| 111 | beq cgl3 | Set background color if bit EQ 0
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| 112 |
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| 113 | or.w d3,d0 | OR foreground color into output word
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| 114 | bra cgl4 | Go update CG word
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| 115 |
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| 116 | cgl3: or.w d4,d0 | OR background color into output word
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| 117 |
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| 118 | cgl4: lsr.w #1,d1 | Shift CG word right 1 pixel
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| 119 | dbf d2,cgl2 | Loop for first 4 pixels
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| 120 |
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| 121 | move.w d0,(a1)+ | Store first output word in scan line
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| 122 | move.w #(HPIX/2)-1,d2 | Set pixel counter in d2
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| 123 |
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| 124 | cgl2a: lsr.w #HSHIFT,d0 | Shift output word right 1 pixel
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| 125 | btst.l #0,d1 | Check CG word ls bit
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| 126 | beq cgl3a | Set background color if bit EQ 0
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| 127 |
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| 128 | or.w d3,d0 | OR foreground color into output word
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| 129 | bra cgl4a | Go update CG word
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| 130 |
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| 131 | cgl3a: or.w d4,d0 | OR background color into output word
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| 132 |
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| 133 | cgl4a: lsr.w #1,d1 | Shift CG word right 1 pixel
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| 134 | dbf d2,cgl2a | Loop for last 4 pixels
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| 135 |
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| 136 | move.w d0,(a1) | Store second output word in scan line
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| 137 | suba.w d5,a1 | Update output pointer
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| 138 | suba.w #2,a1 | ...
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| 139 | adda.l #512,a0 | Update CG pointer for next scan line
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| 140 | dbf d6,cgl1 | Loop for all scan lines
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| 141 |
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| 142 | bra cgl0 | Loop for next character
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| 143 |
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| 144 | cgl5: movem.l (a7)+,d3-d6/a3 | Restore registers
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| 145 | unlk a6 | Unlink stack frames
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| 146 | rts | Return to caller
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| 147 |
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[f40a309] | 148 | .end
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