Q31 Library
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Q31 Library

mikroC PRO for ARM includes a library for operating and working with Q31 fractional number format.

Library Routines

Q31_Abs

Prototype

unsigned long Q31_Abs (long in);
Description

Function calculates absolute value of the Q31 fractional format number.
Parameters
  • in: Q31 input number.
Returns

Function returns Q31 output number.

Q31_Add

Prototype

char Q31_Add(long x, long y, long *z);
Description

Function sums two Q31 format numbers.

If the result exceeds [-2147483648, 2147483647] limits, result will be maximal(minimal) number in Q31 format.
Parameters
  • x: First Q31 number.
  • y: Second Q31 number.
  • z: number pointer to Q31 output number.
Returns
  • 1 - if the result exceeds [-2147483648, 2147483647] limits.
  • 0 - otherwise.

Q31_Sub

Prototype

char Q31_Sub(long x, long y, long *z);
Description

Function subtracts two Q31 format numbers.

If the result exceeds [-2147483648, 2147483647] limits, result will be maximal(minimal) number in Q31 format.
Parameters
  • x: First Q31 number.
  • y: Second Q31 number.
  • z: number pointer to Q31 output number.
Returns
  • 1 - if the result exceeds [-2147483648, 2147483647] limits.
  • 0 - otherwise.

Q31_Itof

Prototype

float Q31_Itof(long x);
Description

Function converts number from the Q31 fractional number format to floating point number format.
Parameters
  • x: input Q31 number, ranging from -2147483648 to 2147483647.
Returns

Function returns resulting floating point number.

Q31_Ftoi

Prototype

long Q31_Ftoi(float f);
Description

Function converts number from the floating point number format to Q31 fractional number format.

Input number scope should be in the range of [-1.00000, 0.99996].

If the floating point number is not in this range, the resulting number will be 0x7FFFFFFF (0x80000000).
Parameters
  • f: floating format number to be converted.
Returns

Function returns resulting Q31 fractional format number.

Q31_Itoa

Prototype

void Q31_Itoa(long x, char *s);
Description

Function converts number from the Q31 fractional format to ASCII string.

Output ASCII string is in the following format : sn.ddddddddddddddddddddddddddddddd

  • s - sign; '-' negative, space - positive.
  • n - integer part; 0 or 1.
  • d - decimal part; 0..9 (ending zeros are not displayed).
Parameters
  • x: Q31 format number to be converted.
  • s: pointer to the resulting ASCII string.
Returns

Nothing.

Q31_Atoi

Prototype

unsigned int Q31_Atoi(char *s, long* out);
Description

Function converts the input ASCII string s into a number in Q31 fractional point format.

Input ASCII string should be in the following format: sn.ddddddddddddddddddddddddddddddd

  • s - sign; '-' negative, space - positive.
  • n - integer part; 0 or 1.
  • d - decimal part; 0..9 (ending zeros are not displayed).
Parameters
  • s: pointer to the input ASCII string.
  • out: pointer to the resulting number in Q31 format.
Returns
  • 2 - If input string is in not in the appropriate format.
  • 1 - If overflow has been detected.
  • 0 - If no errors occured.

Q31_Cos

Prototype

longint Q31_Cos(longint x);
Description

Function returns the cosine of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from 1160290361 to 2147483647.
Parameters
  • x: input number in the Q31 format number, ranging from -2147483648 to 2147483647
Returns

Function returns value in the Q31 format, ranging from 1160290361 to 2147483647.

Q31_Sin

Prototype

longint Q31_Sin(longint x);
Description

Function returns the sine of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from -1807039907 to 1807039904.
Parameters
  • x: input number in the Q31 format number, ranging from -2147483648 to 2147483647.
Returns

Function returns value in the Q31 format, ranging from -1807039907 to 1807039904.

Q31_Tan

Prototype

longint Q31_Tan(longint x);
Description

Function returns the tangent of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from -2147483648 to 2147483648.
Parameters
  • x: input number in the Q31 format number, ranging from -1686629760 to 1686629760.
Returns

Function returns value in the Q31 format, ranging from -2147483648 to 2147483647.

Q31_Asin

Prototype

longint Q31_Asin(longint x);
Description

Function returns the arc sine of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from -2147483648 to 2147483648.
Parameters
  • x: input number in the Q31 format number, ranging from -1807076313 to 1807076320.
Returns

Function returns value in the Q31 format, ranging from -2147483648 to 2147483647.

Q31_Atan

Prototype

longint Q31_Atan(longint x);
Description

Function returns the arc tangent of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from -1673210000 do 1673209982.
Parameters
  • x: input number in the Q31 format number, ranging from -2147483648 to 2147483647.
Returns

Function returns value in the Q31 format, ranging from -1673210000 do 1673209982.

Q31_Acos

Prototype

longint Q31_Acos(longint x);
Description

Function returns the arc cosine of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from 189407136 do 2147458881.
Parameters
  • x: input number in the Q31 format number, ranging from 1160311168 do 2147483647.
Returns

Function returns value in the Q31 format, ranging from 189407136 do 2147458881.

Q31_Log

Prototype

longint Q31_Log(longint x);
Description

Function returns the logarithm of x. The input number is in the Q31 format number and returns value in the Q31 format, ranging from -2144585218 to 0.
Parameters
  • x: input number in the Q31 format number, ranging from 214748368 do 2147483647.
Returns

Function returns value in the Q31 format, ranging from -2144585218 to 0.
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