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;;; read/write binary (sound) files
;;;
;;; names are read|write b|l int|float n,
;;; so read-bint32 reads the next 4 bytes from the current input port,
;;; interpreting them as a big-endian 32-bit integer
(provide 'snd-binary-io.scm)
;;; -------- strings (0-terminated)
(define (io-read-string)
(do ((chars ())
(c (read-byte) (read-byte)))
((or (eof-object? c)
(= c 0))
(reverse (apply string chars)))
(set! chars (cons (integer->char c) chars))))
(define (io-write-string str)
(format () "~{~A~}" str)
;(for-each write-char str)
(write-byte 0))
;;; -------- strings (unterminated)
(define* (read-chars (len 4))
(read-string len))
#|
(do ((str (make-string len))
(i 0 (+ i 1)))
((= i len) str)
(set! (str i) (read-char))))
|#
(define (write-chars str)
(format () "~{~A~}" str))
; (for-each write-char str))
;;; -------- 16-bit ints
(define (read-bint16)
(let ((int (+ (ash (read-byte) 8) (read-byte)))) ; this depends on arg evaluation left->right
(if (> int 32767)
(- int 65536)
int)))
(define (read-lint16)
(let ((int (+ (read-byte) (ash (read-byte) 8))))
(if (> int 32767)
(- int 65536)
int)))
(define (write-bint16 int)
(write-byte (logand (ash int -8) #xff))
(write-byte (logand int #xff)))
(define (write-lint16 int)
(write-byte (logand int #xff))
(write-byte (logand (ash int -8) #xff)))
;;; -------- 32-bit ints
(define (read-bint32)
(let ((int (+ (ash (read-byte) 24) (ash (read-byte) 16) (ash (read-byte) 8) (read-byte))))
(if (> int 2147483647)
(- int 4294967296)
int)))
(define (read-lint32)
(let ((int (+ (read-byte) (ash (read-byte) 8) (ash (read-byte) 16) (ash (read-byte) 24))))
(if (> int 2147483647)
(- int 4294967296)
int)))
(define (write-bint32 int)
(for-each write-byte (vector (logand (ash int -24) 255)
(logand (ash int -16) 255)
(logand (ash int -8) 255)
(logand int 255))))
(define (write-lint32 int)
(for-each write-byte (vector (logand int 255)
(logand (ash int -8) 255)
(logand (ash int -16) 255)
(logand (ash int -24) 255))))
;;; -------- 64-bit ints
(define (read-bint64)
(do ((int 0)
(i 56 (- i 8)))
((< i 0) int)
(set! int (logior int (ash (read-byte) i)))))
(define (read-lint64)
(do ((int 0)
(i 0 (+ i 8)))
((= i 64) int)
(set! int (logior int (ash (read-byte) i)))))
(define (write-bint64 int)
(do ((i 56 (- i 8)))
((< i 0))
(write-byte (logand (ash int (- i)) #xff))))
(define (write-lint64 int)
(do ((i 0 (+ i 8)))
((= i 64))
(write-byte (logand (ash int (- i)) #xff))))
;;; -------- 32-bit floats (IEEE 754, sign + 23(+1) bits significand + 8 bits exponent)
(define (int_to_float32 int)
(if (zero? int)
0.0
(* (if (zero? (ash int -31)) 1.0 -1.0)
(expt 2 (- (logand (ash int -23) #xff) 127))
(logior #x800000 (logand int #x7fffff))
(expt 2 -23))))
(define (read-bfloat32)
(int_to_float32 (read-bint32)))
(define (read-lfloat32)
(int_to_float32 (read-lint32)))
(define (float64_to_int32 flt)
(let ((data (integer-decode-float flt)))
(let ((signif (car data))
(expon (cadr data))
(sign (caddr data)))
(if (= expon signif 0)
0
;; we're assuming floats are (64-bit) doubles in s7, so this is coercing to a 32-bit float in a sense
;; this causes some round-off error
(logior (if (negative? sign) #x80000000 0)
(ash (+ expon 179) 23) ; 179 = (+ 52 127)
(logand (ash signif -29) #x7fffff))))))
(define (write-bfloat32 flt)
(write-bint32 (float64_to_int32 flt)))
(define (write-lfloat32 flt)
(write-lint32 (float64_to_int32 flt)))
;;; -------- 64-bit floats (IEEE 754, sign + 52(+1) bits significand + 11 bits exponent)
(define (int_to_float64 int)
(if (zero? int)
0.0
(* (if (zero? (ash int -63)) 1.0 -1.0)
(expt 2 (- (logand (ash int -52) #x7ff) 1023))
(logior #x10000000000000 (logand int #xfffffffffffff))
(expt 2 -52))))
(define (read-bfloat64)
(int_to_float64 (read-bint64)))
(define (read-lfloat64)
(int_to_float64 (read-lint64)))
(define (float64_to_int64 flt)
(let ((data (integer-decode-float flt)))
(let ((signif (car data))
(expon (cadr data))
(sign (caddr data)))
(if (= expon signif 0)
0
(logior (if (negative? sign) #x8000000000000000 0)
(ash (+ expon 1075) 52) ; 1075 = (+ 52 1023)
(logand signif #xfffffffffffff))))))
(define (write-bfloat64 flt)
(write-bint64 (float64_to_int64 flt)))
(define (write-lfloat64 flt)
(write-lint64 (float64_to_int64 flt)))
;;; -------- 80-bit floats (IEEE 754, sign + 63(+1) bits significand + 15 bits exponent, needed for aifc headers)
(define (read-bfloat80->int)
(let ((exponent 0)
(sign 0)
(buf (make-vector 10)))
(do ((i 0 (+ i 1)))
((= i 10))
(set! (buf i) (read-byte)))
(set! exponent (logior (ash (buf 0) 8) (buf 1)))
(set! sign (if (not (= (logand exponent #x8000) 0)) 1 0))
(set! exponent (logand exponent #x7FFF))
(let ((mant1 (+ (ash (buf 2) 24) (ash (buf 3) 16) (ash (buf 4) 8) (buf 5)))
(mant0 (+ (ash (buf 6) 24) (ash (buf 7) 16) (ash (buf 8) 8) (buf 9))))
(if (= mant1 mant0 exponent sign 0)
0
(round (* (if (= sign 1) -1 1)
(expt 2.0 (- exponent 16383.0))
(+ (* (expt 2.0 -31.0) mant1)
(* (expt 2.0 -63.0) mant0))))))))
(define (write-int->bfloat80 val)
(let ((exponent 0)
(sign 0)
(mant1 0)
(mant0 0))
(if (negative? val)
(begin
(set! sign 1)
(set! val (- val))))
(if (not (zero? val))
(begin
(set! exponent (round (+ (log val 2.0) 16383.0)))
(set! val (* val (expt 2 (- 16414 exponent)))) ; 16414 = (+ 16383 31)
(set! mant1 (floor val))
(set! val (- val mant1))
(set! mant0 (floor (* val (expt 2 32))))))
(write-byte (logior (ash sign 7) (ash exponent -8)))
(write-byte (logand exponent #xFF))
(do ((i 2 (+ i 1))
(j 24 (- j 8)))
((= i 6))
(write-byte (logand (ash mant1 (- j)) #xFF)))
(do ((i 6 (+ i 1))
(j 24 (- j 8)))
((= i 10))
(write-byte (logand (ash mant0 (- j)) #xFF)))))
;;; -------- "au" (NeXT/Sun) header
(define (read-au-header file)
(with-input-from-file file
(lambda ()
(let ((magic (read-chars)))
(if (not (string=? magic ".snd"))
(error 'bad-header "~A is not an au file" file)
(let* ((data-location (read-bint32))
(data-size (read-bint32))
(sample-type (read-bint32))
(srate (read-bint32))
(chns (read-bint32)))
(list magic data-location data-size sample-type srate chns (io-read-string)))))))) ; io-read-string = comment
(define (write-au-header file chns srate data-size sample-type comment) ; data-size in bytes
;; common sample-types: 1 mulaw, 2 linear_8, 3 linear_16, 4 linear_24, 5 linear_32, 6 float, 5 double, 27 alaw
(with-output-to-file file
(lambda ()
(let* ((comlen (length comment))
(data-location (+ 24 (* 4 (floor (+ 1 (/ comlen 4)))))))
(write-chars ".snd")
(for-each write-bint32 (vector data-location data-size sample-type srate chns))
(let ((curloc 24))
(if (> comlen 0)
(begin
(io-write-string comment)
(set! curloc (+ curloc comlen 1)))) ; io-write-string adds a trailing 0
(do ((i curloc (+ i 1)))
((>= i data-location))
(write-byte 0)))))))
(define (read-aif-header file)
(let ((data-location 0)
(data-size 0)
(sample-type 0)
(srate 0)
(chns 0)
(current-location 0))
(with-input-from-file file
(lambda ()
(let ((magic (read-chars)))
(if (not (string=? magic "FORM"))
(error 'bad-header "~A is not an aif file: ~S" file magic)
(let ((size (read-bint32)) ; why was this commented out? the size is the 4 bytes after "FORM"
(magic (read-chars)))
(set! current-location 12)
(if (not (member magic '("AIFF" "AIFC") string=?))
(error 'bad-header "~A is not an aif file: ~S" file magic)
;; now look for the "SSND" and "COMM" chunks
(call-with-exit
(lambda (return)
(let loop ()
(let ((chunk (read-chars))
(chunk-size (read-bint32)))
(if (odd? chunk-size) (set! chunk-size (+ chunk-size 1)))
(if (string=? chunk "SSND")
(begin
(set! data-location (+ 16 current-location (read-bint32)))
(if (> srate 0)
(return (list magic data-location data-size sample-type srate chns))))
(if (string=? chunk "COMM")
(let ((len 0))
(set! chns (read-bint16))
(set! len (read-bint32))
(set! sample-type (read-bint16))
(set! srate (read-bfloat80->int))
(set! data-size (* len chns sample-type 1/8))
(if (> data-location 0)
(return (list magic data-location data-size sample-type srate chns))))
(do ((i 0 (+ i 1))) ; here we really need built-in file IO stuff!
((= i chunk-size))
(if (eof-object? (read-byte))
(return 'bad-header)))))
(set! current-location (+ 8 chunk-size))
(loop)))))))))))))
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