initial quick implementation

index.js

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+/** JS Implementation of BMIP10-ref.c */
+
+function SetupBMIP10(sample_bits, coded_bits) {
+  const config = {};
+
+  config.sample_states = 1 << sample_bits;
+  config.coded_states = 1 << coded_bits;
+  config.lossy_code_width = (1 << (sample_bits - coded_bits + 1)) - 1;
+  config.lossy_rounding = Math.floor(config.lossy_code_width / 2);
+  config.lossless_codes = Math.floor(config.coded_states / 2);
+  config.lossy_codes = Math.floor(config.coded_states / 2);
+  config.code_tables = 1 + Math.floor(config.coded_states / 2);
+  config.default_table = Math.floor(config.code_tables / 2);
+  config.lowest_table_thresh = Math.floor(config.lossless_codes / 2);
+  config.highest_table_thresh =
+    config.sample_states - Math.floor(config.lossless_codes / 2);
+  config.lossy_flag = Math.floor((1 << coded_bits) / 2);
+  return config;
+}
+
+function NextTable(config, sample) {
+  if (sample < config.lowest_table_thresh) {
+    return 0;
+  } else if (sample >= config.highest_table_thresh) {
+    return config.lossy_codes;
+  } else {
+    return Math.floor(
+      (sample - config.lowest_table_thresh + config.lossy_rounding) /
+        config.lossy_code_width
+    );
+  }
+}
+
+function EncodeSample(config, table, sample) {
+  const lossless_low = table * config.lossy_code_width;
+  const lossless_high = lossless_low + config.lossless_codes;
+
+  if (sample >= lossless_low && sample < lossless_high) {
+    return sample - lossless_low;
+  } else if (sample < lossless_low) {
+    return config.lossy_flag | Math.floor(sample / config.lossy_code_width);
+  } else {
+    return (
+      config.lossy_flag |
+      (Math.floor((sample - lossless_high) / config.lossy_code_width) + table)
+    );
+  }
+}
+
+function DecodeSample(config, table, code_word) {
+  const index = code_word & ~config.lossy_flag;
+
+  if (code_word & config.lossy_flag) {
+    if (index < table) {
+      return index * config.lossy_code_width + config.lossy_rounding;
+    } else {
+      return (
+        index * config.lossy_code_width +
+        config.lossy_rounding +
+        config.lossless_codes
+      );
+    }
+  } else {
+    return table * config.lossy_code_width + index;
+  }
+}
+
+class Encoder {
+  constructor(sample_bits, coded_bits) {
+    this.config = SetupBMIP10(sample_bits, coded_bits);
+    this.table = this.config.default_table;
+  }
+
+  encode(samples) {
+    const codeout = [];
+    for (let index = 0; index < samples.length; index++) {
+      const sample = samples[index];
+
+      const code_word = EncodeSample(this.config, this.table, sample);
+      const decoded = DecodeSample(this.config, this.table, code_word);
+      this.table = NextTable(this.config, decoded);
+      // console.log(
+      //   `Used table ${table_old} to encode sample ${sample} to codeword ${code_word}. Decoder will decode ${decoded} so ${
+      //     table === table_old ? "sticking with" : "changing to"
+      //   } table ${table}`
+      // );
+      codeout.push(code_word);
+    }
+    return codeout;
+  }
+
+  reset() {
+    this.pickupTable = this.config.default_table;
+  }
+}
+
+class Decoder {
+  constructor(sample_bits, coded_bits) {
+    this.config = SetupBMIP10(sample_bits, coded_bits);
+    this.table = this.config.default_table;
+  }
+
+  decode(samples) {
+    const sampout = [];
+
+    for (let index = 0; index < samples.length; index++) {
+      const code_word = samples[index];
+      const decoded = DecodeSample(this.config, this.table, code_word);
+      this.table = NextTable(this.config, decoded);
+      this.table_old = this.table;
+      console.log(
+        `Used table ${
+          this.table_old
+        } to decode codeword ${code_word} to sample ${decoded} so ${
+          this.table === this.table_old ? "sticking with" : "changing to"
+        } table ${this.table}`
+      );
+      sampout.push(decoded);
+    }
+    return sampout;
+  }
+
+  reset() {
+    this.pickupTable = this.config.default_table;
+  }
+}
+
+module.exports = {
+  Encoder,
+  Decoder,
+};

package-lock.json

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+{
+  "name": "bmip10",
+  "version": "0.1.0",
+  "lockfileVersion": 3,
+  "requires": true,
+  "packages": {
+    "": {
+      "name": "bmip10",
+      "version": "0.1.0",
+      "license": "ISC"
+    }
+  }
+}

package.json

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+{
+  "name": "bmip10",
+  "version": "0.1.0",
+  "description": "JS implementation of Blackmagic Designs's IP10 codec",
+  "main": "index.js",
+  "keywords": ["Blackmagic", "IP10", "Codec"],
+  "author": {
+    "name": "Joel Wetzell",
+    "email": "me@jwetzell.com",
+    "url": "https://jwetzell.com"
+  },
+  "repository": {
+    "type": "git",
+    "url": "git+https://github.com/jwetzell/bmip10-js.git"
+  },
+  "license": "ISC"
+}

test.js

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+const { Encoder, Decoder } = require("./");
+
+const encoder = new Encoder(10, 8);
+const decoder = new Decoder(10, 8);
+
+const rawData = [1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 144, 233, 377, 610, 987];
+
+const encodedData = encoder.encode(rawData);
+const decodedData = decoder.decode(encodedData);
+console.log(encodedData);
+console.log(decodedData);