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