index.js 1.1 KB

1234567891011121314151617181920212223242526272829303132333435363738394041424344454647
  1. // @flow
  2. import { write, read } from "@xtuc/ieee754";
  3. /**
  4. * According to https://webassembly.github.io/spec/binary/values.html#binary-float
  5. * n = 32/8
  6. */
  7. export const NUMBER_OF_BYTE_F32 = 4;
  8. /**
  9. * According to https://webassembly.github.io/spec/binary/values.html#binary-float
  10. * n = 64/8
  11. */
  12. export const NUMBER_OF_BYTE_F64 = 8;
  13. export const SINGLE_PRECISION_MANTISSA = 23;
  14. export const DOUBLE_PRECISION_MANTISSA = 52;
  15. export function encodeF32(v: number): Array<number> {
  16. const buffer = [];
  17. write(buffer, v, 0, true, SINGLE_PRECISION_MANTISSA, NUMBER_OF_BYTE_F32);
  18. return buffer;
  19. }
  20. export function encodeF64(v: number): Array<number> {
  21. const buffer = [];
  22. write(buffer, v, 0, true, DOUBLE_PRECISION_MANTISSA, NUMBER_OF_BYTE_F64);
  23. return buffer;
  24. }
  25. export function decodeF32(bytes: Array<Byte>): number {
  26. const buffer = Buffer.from(bytes);
  27. return read(buffer, 0, true, SINGLE_PRECISION_MANTISSA, NUMBER_OF_BYTE_F32);
  28. }
  29. export function decodeF64(bytes: Array<Byte>): number {
  30. const buffer = Buffer.from(bytes);
  31. return read(buffer, 0, true, DOUBLE_PRECISION_MANTISSA, NUMBER_OF_BYTE_F64);
  32. }