51 lines
1.4 KiB
Racket
51 lines
1.4 KiB
Racket
#lang racket/base
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;; Pretty hex dump output of a Bytes.
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(provide dump-bytes!)
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;; Exact Exact -> String
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;; Returns the "0"-padded, width-digit hex representation of n
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(define (hex width n)
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(define s (number->string n 16))
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(define slen (string-length s))
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(cond
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((< slen width) (string-append (make-string (- width slen) #\0) s))
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((= slen width) s)
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((> slen width) (substring s 0 width))))
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;; Bytes Exact -> Void
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;; Prints a pretty hex/ASCII dump of bs on (current-output-port).
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(define (dump-bytes! bs [requested-count (bytes-length bs)])
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(define count (min requested-count (bytes-length bs)))
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(define clipped (subbytes bs 0 count))
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(define (dump-hex i)
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(if (< i count)
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(display (hex 2 (bytes-ref clipped i)))
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(display " "))
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(display #\space))
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(define (dump-char i)
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(if (< i count)
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(let ((ch (bytes-ref clipped i)))
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(if (<= 32 ch 127)
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(display (integer->char ch))
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(display #\.)))
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(display #\space)))
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(define (for-each-between f low high)
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(do ((i low (+ i 1)))
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((= i high))
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(f i)))
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(define (dump-line i)
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(display (hex 8 i))
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(display #\space)
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(for-each-between dump-hex i (+ i 8))
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(display ": ")
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(for-each-between dump-hex (+ i 8) (+ i 16))
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(display #\space)
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(for-each-between dump-char i (+ i 8))
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(display " : ")
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(for-each-between dump-char (+ i 8) (+ i 16))
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(newline))
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(do ((i 0 (+ i 16)))
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((>= i count))
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(dump-line i)))
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