?? basic_op.c
字號:
| Inputs : |
| |
| L_var3 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| var1 |
| 16 bit short signed integer (Word16) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| var2 |
| 16 bit short signed integer (Word16) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Outputs : |
| |
| none |
| |
| Return Value : |
| |
| L_var_out |
| 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var_out <= 0x7fff ffff. |
| |
| Caution : |
| |
| In some cases the Carry flag has to be cleared or set before using op- |
| rators which take into account its value. |
|___________________________________________________________________________|
*/
Word32 L_macNs(Word32 L_var3, Word16 var1, Word16 var2)
{
Word32 L_var_out;
L_var_out = L_mult(var1,var2);
L_var_out = L_add_c(L_var3,L_var_out);
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_msuNs |
| |
| Purpose : |
| |
| Multiply var1 by var2 and shift the result left by 1. Subtract the 32 |
| bit result from L_var3 without saturation, return a 32 bit result. Ge- |
| nerate carry and overflow values : |
| L_msuNs(L_var3,var1,var2) = L_sub_c(L_var3,(L_mult(var1,var2)). |
| |
| Complexity weight : 1 |
| |
| Inputs : |
| |
| L_var3 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| var1 |
| 16 bit short signed integer (Word16) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| var2 |
| 16 bit short signed integer (Word16) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Outputs : |
| |
| none |
| |
| Return Value : |
| |
| L_var_out |
| 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var_out <= 0x7fff ffff. |
| |
| Caution : |
| |
| In some cases the Carry flag has to be cleared or set before using op- |
| rators which take into account its value. |
|___________________________________________________________________________|
*/
Word32 L_msuNs(Word32 L_var3, Word16 var1, Word16 var2)
{
Word32 L_var_out;
L_var_out = L_mult(var1,var2);
L_var_out = L_sub_c(L_var3,L_var_out);
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_add |
| |
| Purpose : |
| |
| 32 bits addition of the two 32 bits variables (L_var1+L_var2) with |
| overflow control and saturation; the result is set at +214783647 when |
| overflow occurs or at -214783648 when underflow occurs. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| L_var1 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| L_var2 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| Outputs : |
| |
| none |
| |
| Return Value : |
| |
| L_var_out |
| 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var_out <= 0x7fff ffff. |
|___________________________________________________________________________|
*/
Word32 L_add(Word32 L_var1, Word32 L_var2)
{
Word32 L_var_out;
L_var_out = L_var1 + L_var2;
if (((L_var1 ^ L_var2) & MIN_32) == 0)
{
if ((L_var_out ^ L_var1) & MIN_32)
{
L_var_out = (L_var1 < 0) ? MIN_32 : MAX_32;
Overflow = 1;
}
}
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_sub |
| |
| Purpose : |
| |
| 32 bits subtraction of the two 32 bits variables (L_var1-L_var2) with |
| overflow control and saturation; the result is set at +214783647 when |
| overflow occurs or at -214783648 when underflow occurs. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| L_var1 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| L_var2 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| Outputs : |
| |
| none |
| |
| Return Value : |
| |
| L_var_out |
| 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var_out <= 0x7fff ffff. |
|___________________________________________________________________________|
*/
Word32 L_sub(Word32 L_var1, Word32 L_var2)
{
Word32 L_var_out;
L_var_out = L_var1 - L_var2;
if (((L_var1 ^ L_var2) & MIN_32) != 0)
{
if ((L_var_out ^ L_var1) & MIN_32)
{
L_var_out = (L_var1 < 0L) ? MIN_32 : MAX_32;
Overflow = 1;
}
}
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_add_c |
| |
| Purpose : |
| |
| Performs 32 bits addition of the two 32 bits variables (L_var1+L_var2+C)|
| with carry. No saturation. Generate carry and Overflow values. The car- |
| ry and overflow values are binary variables which can be tested and as- |
| signed values. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| L_var1 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| L_var2 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var3 <= 0x7fff ffff. |
| |
| Outputs : |
| |
| none |
| |
| Return Value : |
| |
| L_var_out |
| 32 bit long signed integer (Word32) whose value falls in the |
| range : 0x8000 0000 <= L_var_out <= 0x7fff ffff. |
| |
| Caution : |
| |
| In some cases the Carry flag has to be cleared or set before using op- |
| rators which take into account its value. |
|___________________________________________________________________________|
*/
Word32 L_add_c(Word32 L_var1, Word32 L_var2)
{
Word32 L_var_out;
Word32 L_test;
Flag carry_int = 0;
L_var_out = L_var1 + L_var2 + Carry;
L_test = L_var1 + L_var2;
if ((L_var1>0) && (L_var2 >0) && (L_test < 0))
{
Overflow = 1;
carry_int = 0;
}
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