When I going to implement 16-Bit addition of 2n Scaled Integer from autosar specification. I didn't get what is a, b and c values in these.
I am going to implement 16-Bit addition of 2n Scaled Integer from autosar specification for mfx modules. in which I get in 8.6.4.1 16-Bit Addition of 2n Scaled Integer in which they specify a Radix point position of the first fixed point operand. Must be a constant expression. b Radix point position of the second fixed point operand. Must be a constant expression. c Radix point position of the fixed point result. Must be a constant expression.
Valid range: 0 ≤ |a - b| ≤ 15
(c - b) ≤ 15, (a - c) ≤ 15, a ≥ b
(c - a) ≤ 15, (b - c) ≤ 15, a < b
But I don't understand How will I get the range value for c.
for below condition
#include "stdio.h"
void main()
{
if(a > =b)
C = 2^(c-a) * [x + (y * 2^(a-b))]
else
C = 2^(c-b) * [(x * 2^(b-a)) + y].
}
What will be the ans if x =10, y=10, and a=20, b=10, and c= 100;
It seems you have a problem converting a maths equation to C source code. Please note that in maths, 2^n means raise 2 to the power n. Thus m*2^n means m*2^abs(n) if n >=0, and means m/(2^abs(n)) if n < 0.
Thus, reading the spec, page 53-54, we have for example:
#include <stdint.h>
uint16_t Mfx_AddP2_u16u16_u16(uint16_t x, uint16_t y, int16_t a, int16_t b, int16_t c)
{
if(a>=b)
{
if(((a-b)>15) || ((c-b)>15) || ((a-c)>15))
{
//SWS_Mfx_00154 - saturate to boundary value
return UINT16_MAX;
}
else
{
uint32_t baseValue = (UINT32_C(1) << (a-b)) * y + x;
if(c>=a)
{
return (uint16_t)(baseValue << (c-a));
}
else
{
//SWS_Mfx_00155 - round to zero
return (uint16_t)(baseValue >> (a-c));
}
}
}
else
{
if(((b-a)>15) || ((c-a)>15) || ((b-c)>15))
{
//SWS_Mfx_00154 - saturate to boundary value
return UINT16_MAX;
}
else
{
uint32_t baseValue = (UINT32_C(1) << (b-a)) * x + y;
if(c>=b)
{
return (uint16_t)(baseValue << (c-b));
}
else
{
//SWS_Mfx_00155 - round to zero
return (uint16_t)(baseValue >> (b-c));
}
}
}
}
I trust you can similarly complete the functions declared below:
uint16_t Mfx_AddP2_u16s16_u16(uint16_t x, int16_t y, int16_t a, int16_t b, int16_t c);
uint16_t Mfx_AddP2_s16s16_u16( int16_t x, int16_t y, int16_t a, int16_t b, int16_t c);
int16_t Mfx_AddP2_u16u16_s16(uint16_t x, uint16_t y, int16_t a, int16_t b, int16_t c);
int16_t Mfx_AddP2_u16s16_s16(uint16_t x, int16_t y, int16_t a, int16_t b, int16_t c);
int16_t Mfx_AddP2_s16s16_s16( int16_t x, int16_t y, int16_t a, int16_t b, int16_t c);
Note: be careful of signed parameters and return values.
Edit: Answering actual question
Given you ask what the result will be when x =10, y=10, and a=20, b=10, and c= 100; Check:
So, in terms of SWS_Mfx_00154, the result must be
, and