more structifying
parent
85ae442385
commit
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#lang racket/base
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/glyph/CFFGlyph.js
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|#
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#;(define-subclass Glyph (CFFGlyph)
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(error 'cff-glyph-unimplemented)
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#;(define/override (_getName this)
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(->m any/c)
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(if (send (· this _font) _getTable 'CFF2)
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(super _getName)
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(send (send (· this _font) _getTable 'CFF_) getGlyphName (· this id))))
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(as-methods
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#;_getName
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#;bias
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#;_getPath))
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@ -0,0 +1,204 @@
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#lang racket/base
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(require (for-syntax racket/base)
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racket/match
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racket/list
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racket/class
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"glyph.rkt"
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sugar/unstable/dict
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sugar/unstable/js
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xenomorph
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racket/struct)
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(provide (all-defined-out))
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#|
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approximates
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https://github.com/mbutterick/fontkit/blob/master/src/glyph/TTFGlyph.js
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|#
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;; Represents a TrueType glyph.
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#;(define-subclass Glyph (TTFGlyph)
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(inherit-field _font id))
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(struct ttf-glyph glyph () #:transparent)
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(define (+ttf-glyph . args)
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(apply +glyph #:constructor ttf-glyph args))
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;; The header for both simple and composite glyphs
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(define GlyfHeader (+Struct
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(dictify 'numberOfContours int16be ;; if negative, this is a composite glyph
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'xMin int16be
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'yMin int16be
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'xMax int16be
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'yMax int16be)))
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;; Flags for simple glyphs
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(define-syntax (define-flag-series stx)
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(syntax-case stx ()
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[(_ . IDS)
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#`(match-define (list . IDS) (map (λ (x) (expt 2 x)) (range #,(length (syntax->list #'IDS)))))]))
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;; Flags for simple glyphs
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(define-flag-series ON_CURVE
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X_SHORT_VECTOR
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Y_SHORT_VECTOR
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REPEAT
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SAME_X
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SAME_Y)
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;; Flags for composite glyphs
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(define-flag-series ARG_1_AND_2_ARE_WORDS
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ARGS_ARE_XY_VALUES
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ROUND_XY_TO_GRID
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WE_HAVE_A_SCALE
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__EMPTY-FLAG___
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MORE_COMPONENTS
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WE_HAVE_AN_X_AND_Y_SCALE
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WE_HAVE_A_TWO_BY_TWO
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WE_HAVE_INSTRUCTIONS
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USE_MY_METRICS
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OVERLAP_COMPOUND
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SCALED_COMPONENT_OFFSET
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UNSCALED_COMPONENT_OFFSET)
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;; Represents a point in a simple glyph
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(struct Point (onCurve endContour x y) #:transparent #:mutable)
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(define (+Point onCurve endContour [x 0] [y 0])
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(Point onCurve endContour x y))
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(define (copy pt)
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(apply +Point (struct->list pt)))
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;; Represents a component in a composite glyph
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(struct Component (glyphID dx dy pos scaleX scaleY scale01 scale10) #:transparent #:mutable)
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(define (+Component glyphID dx dy [pos 0]
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[scaleX 1]
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[scaleY 1]
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[scale01 0]
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[scale10 0])
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(Component glyphID dx dy pos scaleX scaleY scale01 scale10))
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;; Parses just the glyph header and returns the bounding box
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#;(define/override (_getCBox internal)
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(unfinished))
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;; Parses a single glyph coordinate
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(define (_parseGlyphCoord port prev short same)
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(unless (input-port? port)
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(raise-argument-error '_parseGlyphCoord "input port" port))
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(unless (number? prev)
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(raise-argument-error '_parseGlyphCoord "number" prev))
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(unless (and (boolean? short) (boolean? same))
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(raise-argument-error '_parseGlyphCoord "booleans" (list short same)))
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(+ prev (if short
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((if (not same) - +) (decode uint8 port))
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(if same 0 (decode int16be port)))))
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;; Decodes the glyph data into points for simple glyphs,
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;; or components for composite glyphs
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(define (glyph-decode ttfg)
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(define offsets (· (glyph-_font ttfg) loca offsets))
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(match-define (list glyfPos nextPos) (take (drop offsets (glyph-id ttfg)) 2))
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;; Nothing to do if there is no data for this glyph
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(and (not (= glyfPos nextPos))
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(let ()
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(define port (send (glyph-_font ttfg) _getTableStream 'glyf))
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(pos port (+ (pos port) glyfPos))
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(define startPos (pos port))
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(define glyph-data (decode GlyfHeader port))
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(match (· glyph-data numberOfContours)
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[(? positive?) (_decodeSimple glyph-data port)]
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[(? negative?) (_decodeComposite glyph-data port startPos)])
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glyph-data)))
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(define (_decodeSimple glyph-data port)
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(unless (dict? glyph-data)
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(raise-argument-error 'TTFGlyph-_decodeSimple "decoded RGlyfHeader" glyph-data))
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(unless (input-port? port)
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(raise-argument-error 'TTFGlyph-_decodeSimple "input port" port))
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;; this is a simple glyph
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(dict-set! glyph-data 'points empty)
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(define endPtsOfContours (decode (+Array uint16be (· glyph-data numberOfContours)) port))
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(dict-set! glyph-data 'instructions (decode (+Array uint8be uint16be) port))
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(define numCoords (add1 (last endPtsOfContours)))
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(define flags
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(for*/lists (flags)
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([i (in-naturals)]
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#:break (= (length flags) numCoords)
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[flag (in-value (decode uint8 port))]
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[count (in-range (add1 (if (not (zero? (bitwise-and flag REPEAT)))
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(decode uint8 port)
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0)))])
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flag))
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(match-define-values
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(points _ _)
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(for/fold ([points empty] [px 0] [py 0])
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([(flag i) (in-indexed flags)])
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(define point (+Point (zero? (bitwise-and flag ON_CURVE)) (and (index-of endPtsOfContours i) #t) 0 0))
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(define next-px (_parseGlyphCoord port px (not (zero? (bitwise-and flag X_SHORT_VECTOR))) (not (zero? (bitwise-and flag SAME_X)))))
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(define next-py (_parseGlyphCoord port py (not (zero? (bitwise-and flag Y_SHORT_VECTOR))) (not (zero? (bitwise-and flag SAME_Y)))))
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(set-Point-x! point next-px)
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(set-Point-y! point next-py)
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(values (cons point points) next-px next-py)))
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(dict-set! glyph-data 'points (reverse points)))
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(define (_decodeComposite glyph-data port [offset 0])
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;; this is a composite glyph
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(dict-set! glyph-data 'components empty)
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(define haveInstructions #f)
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(define flags MORE_COMPONENTS)
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(dict-set! glyph-data 'components
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(for/list ([i (in-naturals)]
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#:break (zero? (bitwise-and flags MORE_COMPONENTS)))
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(set! flags (send uint16be decode port))
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(define gPos (- (pos port) offset))
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(define glyphID (send uint16be decode port))
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(unless haveInstructions
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(set! haveInstructions (not (zero? (bitwise-and flags WE_HAVE_INSTRUCTIONS)))))
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(match-define
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(list dx dy)
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(let ([decoder (if (not (zero? (bitwise-and flags ARG_1_AND_2_ARE_WORDS))) int16be int8)])
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(list (send decoder decode port) (send decoder decode port))))
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(define component (+Component glyphID dx dy))
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(set-Component-pos! component gPos)
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(cond
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[(not (zero? (bitwise-and flags WE_HAVE_A_SCALE)))
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(define scale (read-fixed14 port))
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(set-Component-scaleX! component scale)
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(set-Component-scaleY! component scale)]
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[(not (zero? (bitwise-and flags WE_HAVE_AN_X_AND_Y_SCALE)))
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(set-Component-scaleX! component (read-fixed14 port))
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(set-Component-scaleY! component (read-fixed14 port))]
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[(not (zero? (bitwise-and flags WE_HAVE_A_TWO_BY_TWO)))
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(set-Component-scaleX! component (read-fixed14 port))
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(set-Component-scale01! component (read-fixed14 port))
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(set-Component-scale10! component (read-fixed14 port))
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(set-Component-scaleY! component (read-fixed14 port))])
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component))
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haveInstructions)
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(define (bytes->fixed14 b1 b2)
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(/ (+ (* b1 (expt 2 8)) b2) (expt 2 14) 1.0))
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(define (read-fixed14 stream)
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(define b1 (send uint8 decode stream))
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(define b2 (send uint8 decode stream))
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(bytes->fixed14 b1 b2))
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