?? mathhalf.c
字號:
if (var1 < 0)
swOut = negate(var1);
else
swOut = var1;
}
return(swOut);
}
/***************************************************************************
*
* FUNCTION NAME: L_abs
*
* PURPOSE:
*
* Take the absolute value of the 32 bit input. An input of
* -0x8000 0000 results in a return value of 0x7fff ffff.
*
* INPUTS:
*
* L_var1
* 32 bit long signed integer (Longword) whose value
* falls in the range
* 0x8000 0000 <= L_var1 <= 0x7fff ffff.
*
* OUTPUTS:
*
* none
*
* RETURN VALUE:
*
* L_Out
* 32 bit long signed integer (Longword) whose value
* falls in the range
* 0x8000 0000 <= L_var1 <= 0x7fff ffff.
*
*
*
* KEYWORDS: absolute value, abs
*
*************************************************************************/
Longword L_abs(Longword L_var1)
{
Longword L_Out;
if (L_var1 == LW_MIN)
L_Out = LW_MAX;
else {
if (L_var1 < 0)
L_Out = -L_var1;
else
L_Out = L_var1;
}
return(L_Out);
}
/*___________________________________________________________________________
| |
| Function Name : L40_add |
| |
| Purpose : |
| |
| 40 bits addition of 40 bits accumulator with 32 bits variable (L_var1) |
| with overflow control and saturation; the result is set at MAX40 |
| when overflow occurs or at MIN40 when underflow occurs. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| L_var1 32 bit long signed integer (Longword) whose value falls in the |
| range : 0x8000 0000 <= L_var1 <= 0x7fff ffff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_add(Word40 acc, Longword L_var1)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
acc = acc + (Word40)L_var1;
if (acc > MAX_40){
acc = MAX_40;
/* Overflow = 1; */
}
if (acc < MIN_40){
acc = MIN_40;
/* Overflow = 1; */
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_sub |
| |
| Purpose : |
| |
| 40 bits subtraction of 40 bits accumulator with 32 bits variable |
| (L_var1) with overflow control and saturation; the result is set at |
| MAX40 when overflow occurs or at MIN40 when underflow occurs. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| L_var1 32 bit long signed integer (Longword) whose value falls in the |
| range : 0x8000 0000 <= L_var1 <= 0x7fff ffff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_sub(Word40 acc, Longword L_var1)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
acc = acc - (Word40)L_var1;
if (acc > MAX_40){
acc = MAX_40;
/* Overflow = 1; */
}
if (acc < MIN_40){
acc = MIN_40;
/* Overflow = 1; */
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_mac |
| |
| Purpose : |
| |
| Multiply var1 by var2 and shift the result left by 1. Add the result |
| to 40 bits accumulator with overflow control and saturation; the result |
| is set at MAX40 when overflow occurs or at MIN40 when underflow occurs. |
| |
| Complexity weight : 1 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| var1 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| var2 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_mac(Word40 acc, Shortword var1, Shortword var2)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
acc = acc + ((Word40)var1 * (Word40)var2 * 2);
if (acc > MAX_40){
acc = MAX_40;
/* Overflow = 1; */
}
if (acc < MIN_40){
acc = MIN_40;
/* Overflow = 1; */
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_msu |
| |
| Purpose : |
| |
| Multiply var1 by var2 and shift the result left by 1. Subtract the |
| result to 40 bits accumulator with overflow control and saturation; |
| the result is set at MAX40 when overflow occurs or at MIN40 when |
| underflow occurs. |
| |
| Complexity weight : 1 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| var1 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| var2 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_msu(Word40 acc, Shortword var1, Shortword var2)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
acc = acc - ((Word40)var1 * (Word40)var2 * 2);
if (acc > MAX_40){
acc = MAX_40;
/* Overflow = 1; */
}
if (acc < MIN_40){
acc = MIN_40;
/* Overflow = 1; */
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_shl |
| |
| Purpose : |
| |
| Arithmetically shift the 40 bits accumulator left var1 positions. Zero |
| fill the var1 LSB of the result. If var1 is negative, arithmetically |
| shift 40 bits accumulator right by -var1 with sign extension. Saturate |
| the result in case of underflows or overflows. | |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| var1 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_shl(Word40 acc, Shortword var1)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
if (var1 < 0){
acc = L40_shr(acc, (Shortword) (-var1));
} else {
for(; var1 > 0; var1--){
acc = acc * 2;
if (acc > MAX_40){
acc = MAX_40;
break;
} else if (acc < MIN_40){
acc = MIN_40;
break;
}
}
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_shr |
| |
| Purpose : |
| |
| Arithmetically shift the 40 bits accumulator right var1 positions with |
| sign extension. If var1 is negative, arithmetically shift 40 bits |
| accumulator left by -var1 and zero fill the var1 LSB of the result. |
| Saturate the result in case of underflows or overflows. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| var1 16 bit short signed integer (Shortword) whose value falls in the |
| range : 0xffff 8000 <= var1 <= 0x0000 7fff. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_shr(Word40 acc, Shortword var1)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
if (var1 < 0){
acc = L40_shl(acc, (Shortword) -var1);
} else {
for ( ; var1 > 0; var1--){
acc = floor(acc * 0.5);
if ((acc == 0) || (acc == -1))
break;
}
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : L40_negate |
| |
| Purpose : |
| |
| Negate the 40 bits accumulator with saturation; saturate to MAX40 in |
| the case where input is MIN40. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| Return Value : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
|___________________________________________________________________________|
*/
Word40 L40_negate(Word40 acc)
{
if ((acc > MAX_40) || (acc < MIN_40) || (acc != floor(acc))){
fprintf(stderr, "BASIC_OP: Error in 40 bits format.\n");
exit(0);
}
acc = -acc;
if (acc > MAX_40){
acc = MAX_40;
}
return(acc);
}
/*___________________________________________________________________________
| |
| Function Name : norm32 |
| |
| Purpose : |
| |
| Produces the number of left shift needed to normalize the 40 bits |
| accumulator in 32 bits format (for positive value on the interval with |
| minimum of 1073741824 and maximum of 2147483647, and for negative value |
| on the interval with minimum of -2147483648 and maximum of -1073741824);|
| in order to normalize the result, the following operation must be done: |
| norm32_acc = L40_shl(acc, norm32(acc)). |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| acc 40 bits accumulator (Word40) whose value falls in the |
| range : MIN40 <= acc <= MAX40. |
| |
| Return Value : |
| |
| var1 16 bit short signed integer (Shortword) whose value falls in the |
| range : -8 <= var_out <= 31. |
|___________________________________________________________________________|
*/
Shortword norm32(Word40 acc)
{
Shortword var1;
if ((acc >?? 快捷鍵說明
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