| ;; Copyright 2010 the V8 project authors. All rights reserved. |
| ;; Redistribution and use in source and binary forms, with or without |
| ;; modification, are permitted provided that the following conditions are |
| ;; met: |
| ;; |
| ;; * Redistributions of source code must retain the above copyright |
| ;; notice, this list of conditions and the following disclaimer. |
| ;; * Redistributions in binary form must reproduce the above |
| ;; copyright notice, this list of conditions and the following |
| ;; disclaimer in the documentation and/or other materials provided |
| ;; with the distribution. |
| ;; * Neither the name of Google Inc. nor the names of its |
| ;; contributors may be used to endorse or promote products derived |
| ;; from this software without specific prior written permission. |
| ;; |
| ;; THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS |
| ;; "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT |
| ;; LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR |
| ;; A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT |
| ;; OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, |
| ;; SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT |
| ;; LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
| ;; DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
| ;; THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
| ;; (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE |
| ;; OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
| |
| ;; This is a Scheme script for the Bigloo compiler. Bigloo must be compiled with |
| ;; support for bignums. The compilation of the script can be done as follows: |
| ;; bigloo -static-bigloo -o generate-ten-powers generate-ten-powers.scm |
| ;; |
| ;; Generate approximations of 10^k. |
| |
| (module gen-ten-powers |
| (static (class Cached-Fast |
| v::bignum |
| e::bint |
| exact?::bool)) |
| (main my-main)) |
| |
| |
| ;;----------------bignum shifts ----------------------------------------------- |
| (define (bit-lshbx::bignum x::bignum by::bint) |
| (if (<fx by 0) |
| #z0 |
| (*bx x (exptbx #z2 (fixnum->bignum by))))) |
| |
| (define (bit-rshbx::bignum x::bignum by::bint) |
| (if (<fx by 0) |
| #z0 |
| (/bx x (exptbx #z2 (fixnum->bignum by))))) |
| |
| ;;----------------the actual power generation ------------------------------- |
| |
| ;; e should be an indication. it might be too small. |
| (define (round-n-cut n e nb-bits) |
| (define max-container (- (bit-lshbx #z1 nb-bits) 1)) |
| (define (round n) |
| (case *round* |
| ((down) n) |
| ((up) |
| (+bx n |
| ;; with the -1 it will only round up if the cut off part is |
| ;; non-zero |
| (-bx (bit-lshbx #z1 |
| (-fx (+fx e nb-bits) 1)) |
| #z1))) |
| ((round) |
| (+bx n |
| (bit-lshbx #z1 |
| (-fx (+fx e nb-bits) 2)))))) |
| (let* ((shift (-fx (+fx e nb-bits) 1)) |
| (cut (bit-rshbx (round n) shift)) |
| (exact? (=bx n (bit-lshbx cut shift)))) |
| (if (<=bx cut max-container) |
| (values cut e exact?) |
| (round-n-cut n (+fx e 1) nb-bits)))) |
| |
| (define (rounded-/bx x y) |
| (case *round* |
| ((down) (/bx x y)) |
| ((up) (+bx (/bx x y) #z1)) |
| ((round) (let ((tmp (/bx (*bx #z2 x) y))) |
| (if (zerobx? (remainderbx tmp #z2)) |
| (/bx tmp #z2) |
| (+bx (/bx tmp #z2) #z1)))))) |
| |
| (define (generate-powers from to mantissa-size) |
| (let* ((nb-bits mantissa-size) |
| (offset (- from)) |
| (nb-elements (+ (- from) to 1)) |
| (vec (make-vector nb-elements)) |
| (max-container (- (bit-lshbx #z1 nb-bits) 1))) |
| ;; the negative ones. 10^-1, 10^-2, etc. |
| ;; We already know, that we can't be exact, so exact? will always be #f. |
| ;; Basically we will have a ten^i that we will *10 at each iteration. We |
| ;; want to create the matissa of 1/ten^i. However the mantissa must be |
| ;; normalized (start with a 1). -> we have to shift the number. |
| ;; We shift by multiplying with two^e. -> We encode two^e*(1/ten^i) == |
| ;; two^e/ten^i. |
| (let loop ((i 1) |
| (ten^i #z10) |
| (two^e #z1) |
| (e 0)) |
| (unless (< (- i) from) |
| (if (>bx (/bx (*bx #z2 two^e) ten^i) max-container) |
| ;; another shift would make the number too big. We are |
| ;; hence normalized now. |
| (begin |
| (vector-set! vec (-fx offset i) |
| (instantiate::Cached-Fast |
| (v (rounded-/bx two^e ten^i)) |
| (e (negfx e)) |
| (exact? #f))) |
| (loop (+fx i 1) (*bx ten^i #z10) two^e e)) |
| (loop i ten^i (bit-lshbx two^e 1) (+fx e 1))))) |
| ;; the positive ones 10^0, 10^1, etc. |
| ;; start with 1.0. mantissa: 10...0 (1 followed by nb-bits-1 bits) |
| ;; -> e = -(nb-bits-1) |
| ;; exact? is true when the container can still hold the complete 10^i |
| (let loop ((i 0) |
| (n (bit-lshbx #z1 (-fx nb-bits 1))) |
| (e (-fx 1 nb-bits))) |
| (when (<= i to) |
| (receive (cut e exact?) |
| (round-n-cut n e nb-bits) |
| (vector-set! vec (+fx i offset) |
| (instantiate::Cached-Fast |
| (v cut) |
| (e e) |
| (exact? exact?))) |
| (loop (+fx i 1) (*bx n #z10) e)))) |
| vec)) |
| |
| (define (print-c powers from to struct-type |
| cache-name max-distance-name offset-name macro64) |
| (define (display-power power k) |
| (with-access::Cached-Fast power (v e exact?) |
| (let ((tmp-p (open-output-string))) |
| ;; really hackish way of getting the digits |
| (display (format "~x" v) tmp-p) |
| (let ((str (close-output-port tmp-p))) |
| (printf " {~a(0x~a, ~a), ~a, ~a},\n" |
| macro64 |
| (substring str 0 8) |
| (substring str 8 16) |
| e |
| k))))) |
| (define (print-powers-reduced n) |
| (print "static const " struct-type " " cache-name |
| "(" n ")" |
| "[] = {") |
| (let loop ((i 0) |
| (nb-elements 0) |
| (last-e 0) |
| (max-distance 0)) |
| (cond |
| ((>= i (vector-length powers)) |
| (print " };") |
| (print "static const int " max-distance-name "(" n ") = " |
| max-distance ";") |
| (print "// nb elements (" n "): " nb-elements)) |
| (else |
| (let* ((power (vector-ref powers i)) |
| (e (Cached-Fast-e power))) |
| (display-power power (+ i from)) |
| (loop (+ i n) |
| (+ nb-elements 1) |
| e |
| (cond |
| ((=fx i 0) max-distance) |
| ((> (- e last-e) max-distance) (- e last-e)) |
| (else max-distance)))))))) |
| (print "// Copyright 2010 the V8 project authors. All rights reserved.") |
| (print "// ------------ GENERATED FILE ----------------") |
| (print "// command used:") |
| (print "// " |
| (apply string-append (map (lambda (str) |
| (string-append " " str)) |
| *main-args*)) |
| " // NOLINT") |
| (print) |
| (print |
| "// This file is intended to be included inside another .h or .cc files\n" |
| "// with the following defines set:\n" |
| "// GRISU_CACHE_STRUCT: should expand to the name of a struct that will\n" |
| "// hold the cached powers of ten. Each entry will hold a 64-bit\n" |
| "// significand, a 16-bit signed binary exponent, and a 16-bit\n" |
| "// signed decimal exponent. Each entry will be constructed as follows:\n" |
| "// { significand, binary_exponent, decimal_exponent }.\n" |
| "// GRISU_CACHE_NAME(i): generates the name for the different caches.\n" |
| "// The parameter i will be a number in the range 1-20. A cache will\n" |
| "// hold every i'th element of a full cache. GRISU_CACHE_NAME(1) will\n" |
| "// thus hold all elements. The higher i the fewer elements it has.\n" |
| "// Ideally the user should only reference one cache and let the\n" |
| "// compiler remove the unused ones.\n" |
| "// GRISU_CACHE_MAX_DISTANCE(i): generates the name for the maximum\n" |
| "// binary exponent distance between all elements of a given cache.\n" |
| "// GRISU_CACHE_OFFSET: is used as variable name for the decimal\n" |
| "// exponent offset. It is equal to -cache[0].decimal_exponent.\n" |
| "// GRISU_UINT64_C: used to construct 64-bit values in a platform\n" |
| "// independent way. In order to encode 0x123456789ABCDEF0 the macro\n" |
| "// will be invoked as follows: GRISU_UINT64_C(0x12345678,9ABCDEF0).\n") |
| (print) |
| (print-powers-reduced 1) |
| (print-powers-reduced 2) |
| (print-powers-reduced 3) |
| (print-powers-reduced 4) |
| (print-powers-reduced 5) |
| (print-powers-reduced 6) |
| (print-powers-reduced 7) |
| (print-powers-reduced 8) |
| (print-powers-reduced 9) |
| (print-powers-reduced 10) |
| (print-powers-reduced 11) |
| (print-powers-reduced 12) |
| (print-powers-reduced 13) |
| (print-powers-reduced 14) |
| (print-powers-reduced 15) |
| (print-powers-reduced 16) |
| (print-powers-reduced 17) |
| (print-powers-reduced 18) |
| (print-powers-reduced 19) |
| (print-powers-reduced 20) |
| (print "static const int GRISU_CACHE_OFFSET = " (- from) ";")) |
| |
| ;;----------------main -------------------------------------------------------- |
| (define *main-args* #f) |
| (define *mantissa-size* #f) |
| (define *dest* #f) |
| (define *round* #f) |
| (define *from* #f) |
| (define *to* #f) |
| |
| (define (my-main args) |
| (set! *main-args* args) |
| (args-parse (cdr args) |
| (section "Help") |
| (("?") (args-parse-usage #f)) |
| ((("-h" "--help") (help "?, -h, --help" "This help message")) |
| (args-parse-usage #f)) |
| (section "Misc") |
| (("-o" ?file (help "The output file")) |
| (set! *dest* file)) |
| (("--mantissa-size" ?size (help "Container-size in bits")) |
| (set! *mantissa-size* (string->number size))) |
| (("--round" ?direction (help "Round bignums (down, round or up)")) |
| (set! *round* (string->symbol direction))) |
| (("--from" ?from (help "start at 10^from")) |
| (set! *from* (string->number from))) |
| (("--to" ?to (help "go up to 10^to")) |
| (set! *to* (string->number to))) |
| (else |
| (print "Illegal argument `" else "'. Usage:") |
| (args-parse-usage #f))) |
| (when (not *from*) |
| (error "generate-ten-powers" |
| "Missing from" |
| #f)) |
| (when (not *to*) |
| (error "generate-ten-powers" |
| "Missing to" |
| #f)) |
| (when (not *mantissa-size*) |
| (error "generate-ten-powers" |
| "Missing mantissa size" |
| #f)) |
| (when (not (memv *round* '(up down round))) |
| (error "generate-ten-powers" |
| "Missing round-method" |
| *round*)) |
| |
| (let ((dividers (generate-powers *from* *to* *mantissa-size*)) |
| (p (if (not *dest*) |
| (current-output-port) |
| (open-output-file *dest*)))) |
| (unwind-protect |
| (with-output-to-port p |
| (lambda () |
| (print-c dividers *from* *to* |
| "GRISU_CACHE_STRUCT" "GRISU_CACHE_NAME" |
| "GRISU_CACHE_MAX_DISTANCE" "GRISU_CACHE_OFFSET" |
| "GRISU_UINT64_C" |
| ))) |
| (if *dest* |
| (close-output-port p))))) |
