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126 lines
2.7 KiB
126 lines
2.7 KiB
(
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; This program parses and shows bmp.
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; Only 32-bit RGB format is supported at the moment.
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;
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; To run it:
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; cat pika-rgb32.bmp | crsn bmp-parser.csn
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(def HUGEPIXELS 1)
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(ld r0 @cin_r)(cmp r0 'B' (ne? (fault "Bad magic")))
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(ld r1 @cin_r)(cmp r1 'M' (ne? (fault "Bad magic")))
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(ldn _ @cin_r 8)
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(sym datastart r6)
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(call rd4) (ld datastart res0)
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(sym hlen r7)
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(call rd4) (ld hlen res0)
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(sym w r8) (sym h r9)
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(call rd4) (ld w res0)
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(call rd4) (ld h res0)
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(ldn _ @cin_r 2) ; planes
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(sym bits r10)
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(call rd2) (ld bits res0)
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(call rd4) (tst res0 (nz? (fault "Compression not implemented")))
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(ldn _ @cin_r 12) ; image size + resolutions
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(sym usedcolors r11)
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(call rd4) (ld usedcolors res0)
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(ldn _ @cin_r 4) ; read to the end of the 40-byte header
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(cmp bits 32 (ne? (fault "Only 32-bit supported now")))
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; Skip the palette if any
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(ld r0 datastart)
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(sub r0 54)
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; Discard bytes until the start of image data. This contains the palette!
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; TODO load to a buffer when indexed BMP support is added
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(ldn _ @cin_r r0)
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(sym x r4)
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(sym y r5)
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(sym dy r12)
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(ld x 0)(ld y h)(ld dy -1)(dec y)
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; test if height is negative
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(and r0 h 0x8000_0000
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(nz?
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(se32 h) ; sign extend to u64
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(mul h -1)
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(ld dy 1) ; going downward
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(ld y 0)
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(dec y)
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))
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(ld r0 w)(ld r1 h)
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(tst HUGEPIXELS (z? (j :nohuge1)))
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(mul r0 8)(mul r1 8)(sub r1 8)
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(:nohuge1)
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(sc-init r0 r1)
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; Here comes the parsing
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(:nx)
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(call rd4)
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(tst HUGEPIXELS
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(z? (sc-px x y res0))
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(nz? (call bigpixel x y res0)))
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(add x 1)
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(cmp x w (ne? (j :nx)))
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(ld x 0)
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(add y dy (z? (j :end)))
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(cmp y h (eq? (j :end)))
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(j :nx)
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(:end)
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(sc-blit)
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(:endl)
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(sc-poll)
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(mslp 10)
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(j :endl)
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(proc bigpixel x y rgb
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(ld r4 x)(ld r1 y)(sub r1 1)
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(mul r4 8)(mul r1 8)
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(ld r2 r4)(add r2 8)
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(ld r3 r1)(add r3 8)
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(ld r0 r4)
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(:nx)
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(sc-px r0 r1 rgb)
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(add r0 1)
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(cmp r0 r2 (ne? (j :nx)))
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(ld r0 r4)
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(add r1 1)
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(cmp r1 r3 (eq? (ret)))
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(j :nx)
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)
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(proc rd4
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; Read 4 bytes as little endian
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(ld8 r0 @cin_r)
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(ld8/8 r0 @cin_r)
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(ld8/16 r0 @cin_r)
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(ld8/24 r0 @cin_r)
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(ret r0)
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)
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(proc rd2
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; Read 2 bytes as little endian
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(ld8 r0 @cin_r)
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(ld8/8 r0 @cin_r)
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(ret r0)
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)
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)
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