diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/lobject.js | 91 | ||||
| -rw-r--r-- | src/lstrlib.js | 28 |
2 files changed, 91 insertions, 28 deletions
diff --git a/src/lobject.js b/src/lobject.js index 58e2d21..fca259d 100644 --- a/src/lobject.js +++ b/src/lobject.js @@ -5,6 +5,7 @@ const assert = require('assert'); const ljstype = require('./ljstype.js'); const lua = require('./lua.js'); +const luaconf = require('./luaconf.js'); const CT = lua.constant_types; const UpVal = require('./lfunc.js').UpVal; @@ -341,9 +342,93 @@ const luaO_utf8desc = function(buff, x) { return n; }; +/* maximum number of significant digits to read (to avoid overflows + even with single floats) */ +const MAXSIGDIG = 30; + +// See: http://croquetweak.blogspot.fr/2014/08/deconstructing-floats-frexp-and-ldexp.html +const frexp = function(value) { + if (value === 0) return [value, 0]; + var data = new DataView(new ArrayBuffer(8)); + data.setFloat64(0, value); + var bits = (data.getUint32(0) >>> 20) & 0x7FF; + if (bits === 0) { // denormal + data.setFloat64(0, value * Math.pow(2, 64)); // exp + 64 + bits = ((data.getUint32(0) >>> 20) & 0x7FF) - 64; + } + var exponent = bits - 1022; + var mantissa = ldexp(value, -exponent); + return [mantissa, exponent]; +}; + +const ldexp = function(mantissa, exponent) { + var steps = Math.min(3, Math.ceil(Math.abs(exponent) / 1023)); + var result = mantissa; + for (var i = 0; i < steps; i++) + result *= Math.pow(2, Math.floor((exponent + i) / steps)); + return result; +}; + + +/* +** convert an hexadecimal numeric string to a number, following +** C99 specification for 'strtod' +*/ +const lua_strx2number = function(s) { + let dot = luaconf.lua_getlocaledecpoint(); + let r = 0.0; /* result (accumulator) */ + let sigdig = 0; /* number of significant digits */ + let nosigdig = 0; /* number of non-significant digits */ + let e = 0; /* exponent correction */ + let neg; /* 1 if number is negative */ + let hasdot = false; /* true after seen a dot */ + + while (ljstype.lisspace(s.charAt(0))) s = s.slice(1); /* skip initial spaces */ + + neg = s.charAt(0) === '-'; /* check signal */ + s = neg || s.charAt(0) === '+' ? s.slice(1) : s; /* skip sign if one */ + if (!(s.charAt(0) === '0' && (s.charAt(1) === 'x' || s.charAt(1) === 'X'))) /* check '0x' */ + return 0.0; /* invalid format (no '0x') */ + + for (s = s.slice(2); ; s = s.slice(1)) { /* skip '0x' and read numeral */ + if (s.charAt(0) === dot) { + if (hasdot) break; /* second dot? stop loop */ + else hasdot = true; + } else if (ljstype.lisxdigit(s.charAt(0))) { + if (sigdig === 0 && s.charAt(0) === '0') /* non-significant digit (zero)? */ + nosigdig++; + else if (++sigdig <= MAXSIGDIG) /* can read it without overflow? */ + r = (r * 16) + luaO_hexavalue(s); + else e++; /* too many digits; ignore, but still count for exponent */ + if (hasdot) e--; /* decimal digit? correct exponent */ + } else break; /* neither a dot nor a digit */ + } + + if (nosigdig + sigdig === 0) /* no digits? */ + return 0.0; /* invalid format */ + e *= 4; /* each digit multiplies/divides value by 2^4 */ + if (s.charAt(0) === 'p' || s.charAt(0) === 'P') { /* exponent part? */ + let exp1 = 0; /* exponent value */ + let neg1; /* exponent signal */ + s = s.slice(1); /* skip 'p' */ + neg1 = s.charAt(0) === '-'; /* check signal */ + s = neg1 || s.charAt(0) === '+' ? s.slice(1) : s; /* skip sign if one */ + if (!ljstype.lisdigit(s.charAt(0))) + return 0.0; /* invalid; must have at least one digit */ + while (ljstype.lisdigit(s.charAt(0))) { /* read exponent */ + exp1 = exp1 * 10 + s.charCodeAt(0) - '0'.charCodeAt(0); + s = s.slice(1); + } + if (neg1) exp1 = -exp1; + e += exp1; + } + if (neg) r = -r; + return s.trim().search(/s/) < 0 ? ldexp(r, e) : null; /* Only valid if nothing left is s*/ +}; + const l_str2dloc = function(s, mode) { - let flt = mode === 'x' ? parseInt(s, '16') : parseFloat(s); - return !isNaN(flt) && /^\d+(\.\d+)?\0?$/.test(s) ? flt : null; /* OK if no trailing characters */ + let flt = mode === 'x' ? lua_strx2number(s) : parseFloat(s); + return !isNaN(flt) ? flt : null; /* OK if no trailing characters */ }; const l_str2d = function(s) { @@ -470,8 +555,10 @@ module.exports.LocVar = LocVar; module.exports.TValue = TValue; module.exports.Table = Table; module.exports.UTF8BUFFSZ = UTF8BUFFSZ; +module.exports.frexp = frexp; module.exports.intarith = intarith; module.exports.jsstring = jsstring; +module.exports.ldexp = ldexp; module.exports.luaO_chunkid = luaO_chunkid; module.exports.luaO_hexavalue = luaO_hexavalue; module.exports.luaO_int2fb = luaO_int2fb; diff --git a/src/lstrlib.js b/src/lstrlib.js index 6e54d4d..471187b 100644 --- a/src/lstrlib.js +++ b/src/lstrlib.js @@ -85,29 +85,6 @@ const SIZELENMOD = luaconf.LUA_NUMBER_FRMLEN.length + 1; const L_NBFD = 1; -// See: http://croquetweak.blogspot.fr/2014/08/deconstructing-floats-frexp-and-ldexp.html -const frexp = function(value) { - if (value === 0) return [value, 0]; - var data = new DataView(new ArrayBuffer(8)); - data.setFloat64(0, value); - var bits = (data.getUint32(0) >>> 20) & 0x7FF; - if (bits === 0) { // denormal - data.setFloat64(0, value * Math.pow(2, 64)); // exp + 64 - bits = ((data.getUint32(0) >>> 20) & 0x7FF) - 64; - } - var exponent = bits - 1022; - var mantissa = ldexp(value, -exponent); - return [mantissa, exponent]; -}; - -const ldexp = function(mantissa, exponent) { - var steps = Math.min(3, Math.ceil(Math.abs(exponent) / 1023)); - var result = mantissa; - for (var i = 0; i < steps; i++) - result *= Math.pow(2, Math.floor((exponent + i) / steps)); - return result; -}; - /* ** Add integer part of 'x' to buffer and return new 'x' */ @@ -126,7 +103,7 @@ const num2straux = function(x) { /* create "0" or "-0" followed by exponent */ return sprintf(luaconf.LUA_NUMBER_FMT + "x0p+0", x).split('').map(e => e.charCodeAt(0)); } else { - let fe = frexp(x); /* 'x' fraction and exponent */ + let fe = lobject.frexp(x); /* 'x' fraction and exponent */ let m = fe[0]; let e = fe[1]; let n = 0; /* character count */ @@ -241,8 +218,7 @@ const addliteral = function(L, b, arg) { checkdp(b); /* ensure it uses a dot */ } else { /* integers */ let n = lapi.lua_tointeger(L, arg); - let format = (n === Number.MIN_SAFE_INTEGER) ? `0x%${luaconf.LUA_INTEGER_FRMLEN}x` : luaconf.LUA_INTEGER_FMT; - concat(b, lua.to_luastring(sprintf(format, n))); + concat(b, lua.to_luastring(sprintf("%d", n))); } break; } |