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Binary data operations by JavaScript TypedArray
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| /** | |
| * Find a character from memory block | |
| * @param {Uint8Array} s Array to find | |
| * @param {Number} c Character to find | |
| * @param {Number} n Length of array in bytes | |
| * @return Zero-based index (if not found, returns -1) | |
| */ | |
| function memchr(s, c, n) { | |
| return s.indexOf(c); | |
| } |
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| /** | |
| * Copy memory block | |
| * @param {Uint8Array} dest Destination | |
| * @param {Uint8Array} src Source | |
| * @param {Number} n Length in bytes | |
| */ | |
| function memcpy(dest, src, n) { | |
| dest.set(src.slice(0, n)) | |
| } | |
| /** | |
| * Copy memory block with offsets | |
| * @param {Uint8Array} dest Destination | |
| * @param {Number} destOffset Offset bytes for destination | |
| * @param {Uint8Array} src Source | |
| * @param {Number} srcOffset Offset bytes for source | |
| * @param {Number} n Length in bytes | |
| */ | |
| function memcpy_offseted(dest, destOffset, src, srcOffset, n) { | |
| dest.set(src.slice(srcOffset, srcOffset + n), destOffset) | |
| } |
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| /** | |
| * Find substring from memory block | |
| * @param {Uint8Array} haystack Array to find | |
| * @param {Number} haystacklen Length of haystack | |
| * @param {Uint8Array} needle Array of substring | |
| * @param {Number} needlelen Length of needle | |
| * @return Zero-based index (if not found, returns -1) | |
| */ | |
| function memmem(haystack, haystacklen, needle, needlelen) { | |
| /* This algorithm may be SLOW */ | |
| var next = 0; | |
| while (next <= (haystacklen - needlelen)) { | |
| var index = haystack.indexOf(needle[0], next); | |
| if (index == -1) { | |
| return -1; | |
| } | |
| var offset; | |
| var found = 1; | |
| for (offset = 1; offset < needlelen; ++offset) { | |
| if (haystack[index + offset] != needle[offset]) { | |
| found = 0; | |
| break; | |
| } | |
| } | |
| if (found) { | |
| return index; | |
| } | |
| next = index + 1; | |
| } | |
| } |
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