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jackerleyjackerley
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Merge pull request #426 from YoYoGames/gmb-4442-buffer-funcs-f16-support
Gmb 4442 buffer funcs f16 support
2 parents 3521c41 + 7f50309 commit dd9ed14

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‎scripts/yyBuffer.js

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@@ -244,6 +244,141 @@ function yyBuffer( _size, _type, _alignment, _srcbytebuff ) {
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}
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}
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// #################################################################################################
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/// Function: yygetFloat16
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/// Description:
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/// Retrieve and decode a 16-bit floating-point number from a DataView.
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///
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/// Parameters:
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/// byteOffset - The offset where the 16-bit float is stored.
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/// littleEndian - Specifies the endianness of the data (true for little-endian, false for big-endian).
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///
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/// Returns:
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/// The decoded 16-bit floating-point number.
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/// If the input data is invalid or out of range, NaN is returned.
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// #################################################################################################
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DataView.prototype.yygetFloat16 = function (byteOffset, littleEndian) {
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// byteOffset: The offset where the 16-bit float is stored
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// littleEndian: Specifies the endianness of the data
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// Used references: https://en.wikipedia.org/wiki/Half-precision_floating-point_format
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// Read the 16-bit float as an unsigned integer
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const uint16 = this.getUint16(byteOffset, littleEndian);
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// Extract the sign bit (bit 15)
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const sign = (uint16 & 0x8000) ? -1 : 1;
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// Extract the exponent bits (bits 10-14)
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const exponent = (uint16 >> 10) & 0x1F;
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// Extract the mantissa bits (bits 0-9)
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const mantissa = uint16 & 0x3FF;
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if (exponent === 0) {
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// If exponent is 0, it's a denormalized number or zero
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if (mantissa === 0) {
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// Zero
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return sign * 0.0;
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} else {
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// Denormalized number
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// Calculate the value using the formula for denormalized numbers
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return sign * Math.pow(2, -14) * (mantissa / 1024);
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}
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} else if (exponent === 31) {
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// If exponent is 31, it's infinity or NaN
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if (mantissa === 0) {
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// Positive or negative infinity
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return (sign === 1) ? Infinity : -Infinity;
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} else {
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// NaN
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return NaN;
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}
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} else {
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// Normalized number
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// Calculate the value using the formula for normalized numbers
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return sign * Math.pow(2, exponent - 15) * (1 + mantissa / 1024);
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}
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};
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// #################################################################################################
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/// Function: yysetFloat16
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/// Description:
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/// Encode and write a 16-bit floating-point number (float16) to a DataView.
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///
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/// Parameters:
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/// offset - The offset where the float16 will be written in the DataView.
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/// value - The float16 value to encode and write.
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/// littleEndian - Optional. Specifies the endianness of the data (true for little-endian, false for big-endian).
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///
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/// Returns:
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/// None.
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///
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/// Details:
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/// The function encodes the provided float16 value as per IEEE 754-2008 standard for half-precision
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/// floating-point numbers and writes it to the specified offset in the DataView. If the value is
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/// outside the representable range for float16, a RangeError is thrown.
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///
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/// Special cases:
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/// - If the value is 0, it is written as a positive zero.
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/// - If the value is NaN, it is written as the NaN representation.
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///
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/// Example Usage:
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/// const dataView = new DataView(new ArrayBuffer(2));
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/// dataView.yysetFloat16(0, 1.0, true); // Write float16 value 1.0 in little-endian
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// #################################################################################################
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DataView.prototype.yysetFloat16 = function(offset, value, littleEndian = true) {
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let sign = 0;
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let exponent = 0;
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let mantissa = 0;
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// Used references: https://en.wikipedia.org/wiki/Half-precision_floating-point_format
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if (isNaN(value)) {
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// If the value is NaN, use the standard NaN representation for float16.
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mantissa = 0x200;
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exponent = 0x1F;
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} else if (value === Infinity || value === -Infinity) {
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// Handling Infinity.
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exponent = 0x1F;
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} else if (value === 0) {
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// Handling zero (both positive and negative).
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sign = (1 / value === -Infinity) ? 0x8000 : 0;
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} else {
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sign = value < 0 ? 0x8000 : 0;
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value = Math.abs(value);
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if (value >= Math.pow(2, -14)) {
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// Handle normal numbers.
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let exponentAndMantissa = Math.floor(Math.log2(value) + 15);
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exponent = exponentAndMantissa;
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mantissa = Math.floor((value / Math.pow(2, exponent - 15) - 1) * 1024);
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if (mantissa === 1024) {
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// We might end in an exponent overflow state.
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exponentAndMantissa += 1;
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exponent = exponentAndMantissa;
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mantissa = 0;
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}
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// Check if we overflow into Infinity.
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if (exponentAndMantissa > 30) {
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// Handle overflow to Infinity.
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exponent = 0x1F;
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mantissa = 0;
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}
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} else {
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// Handle subnormal numbers.
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mantissa = Math.floor(value / Math.pow(2, -24));
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}
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}
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const float16 = sign | (exponent << 10) | mantissa;
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this.setUint16(offset, float16, littleEndian);
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};
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// #############################################################################################
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/// Function:<summary>
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/// Return the size of a "type"
@@ -470,6 +605,11 @@ yyBuffer.prototype.yyb_read = function(_type) {
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res = new Long( this.m_DataView.getUint32(this.m_BufferIndex, true), 0);
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this.m_BufferIndex += 4;
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break;
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case eBuffer_F16:
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res = this.m_DataView.yygetFloat16(this.m_BufferIndex, true);
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this.m_BufferIndex += 2;
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break;
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case eBuffer_F32:
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res = this.m_DataView.getFloat32(this.m_BufferIndex, true);
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this.m_BufferIndex += 4;
@@ -478,6 +618,7 @@ yyBuffer.prototype.yyb_read = function(_type) {
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res = this.m_DataView.getFloat64(this.m_BufferIndex, true);
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this.m_BufferIndex += 8;
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break;
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case eBuffer_U64:
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var low = this.m_DataView.getUint32(this.m_BufferIndex, true);
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this.m_BufferIndex += 4;
@@ -1260,6 +1401,11 @@ yyBuffer.prototype.yyb_write = function(_type, _value) {
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this.m_DataView.setUint32(this.m_BufferIndex, _value, true);
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this.m_BufferIndex += 4;
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break;
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case eBuffer_F16:
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this.m_DataView.yysetFloat16(this.m_BufferIndex, _value, true);
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this.m_BufferIndex += 2;
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break;
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case eBuffer_F32:
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this.m_DataView.setFloat32(this.m_BufferIndex, _value, true);
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this.m_BufferIndex += 4;
@@ -1268,6 +1414,7 @@ yyBuffer.prototype.yyb_write = function(_type, _value) {
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this.m_DataView.setFloat64(this.m_BufferIndex, _value, true);
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this.m_BufferIndex += 8;
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break;
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case eBuffer_U64:
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var int64Val = yyGetInt64(_value);
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this.m_DataView.setUint32(this.m_BufferIndex, int64Val.low, true);
@@ -1336,12 +1483,17 @@ yyBuffer.prototype.yyb_peek = function(_type, _offset) {
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case eBuffer_U32:
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res = this.m_DataView.getUint32(_offset, true);
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break;
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case eBuffer_F16:
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res = this.m_DataView.yygetFloat16(_offset, true);
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break;
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case eBuffer_F32:
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res = this.m_DataView.getFloat32(_offset, true);
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break;
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case eBuffer_F64:
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res = this.m_DataView.getFloat64(_offset, true);
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break;
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case eBuffer_U64:
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var low = this.m_DataView.getUint32(_offset, true);
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var high = this.m_DataView.getUint32(_offset + 4, true);

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