?? basop.c
字號:
*/
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 + (Word32)Carry;
L_test = L_var1 + L_var2;
if ((L_var1 > 0L) && (L_var2 > 0L) && (L_test < 0L)) {
Overflow = 1;
carry_int = 0;
}
else {
if ((L_var1 < 0L) && (L_var2 < 0L) && (L_test > 0L)) {
Overflow = 1;
carry_int = 1;
}
else {
if (((L_var1 ^ L_var2) < 0L) && (L_test > 0L)) {
Overflow = 0;
carry_int = 1;
}
else {
Overflow = 0;
carry_int = 0;
}
}
}
if (Carry) {
if (L_test == MAX_32) {
Overflow = 1;
Carry = carry_int;
}
else {
if (L_test == (Word32) 0xFFFFFFFFL) {
Carry = 1;
}
else {
Carry = carry_int;
}
}
}
else {
Carry = carry_int;
}
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_sub_c |
| |
| Purpose : |
| |
| Performs 32 bits subtraction of the two 32 bits variables with carry |
| (borrow) : L_var1-L_var2-C. No saturation. Generate carry and Overflow |
| values. The carry and overflow values are binary variables which can |
| be tested and assigned 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_sub_c(Word32 L_var1, Word32 L_var2)
{
Word32 L_var_out;
Word32 L_test;
Flag carry_int = 0;
if (Carry) {
Carry = 0;
if (L_var2 != MIN_32) {
L_var_out = L_add_c(L_var1,-L_var2);
}
else {
L_var_out = L_var1 - L_var2;
if (L_var1 > 0L) {
Overflow = 1;
Carry = 0;
}
}
}
else {
L_var_out = L_var1 - L_var2 - (Word32)0X00000001L;
L_test = L_var1 - L_var2;
if ((L_test < 0L) && (L_var1 > 0L) && (L_var2 < 0L)) {
Overflow = 1;
carry_int = 0;
}
else if ((L_test > 0L) && (L_var1 < 0L) && (L_var2 > 0L)) {
Overflow = 1;
carry_int = 1;
}
else if ((L_test > 0L) && ((L_var1 ^ L_var2) > 0L)) {
Overflow = 0;
carry_int = 1;
}
if (L_test == MIN_32) {
Overflow = 1;
Carry = carry_int;
}
else {
Carry = carry_int;
}
}
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : L_negate |
| |
| Purpose : |
| |
| Negate the 32 bit variable L_var1 with saturation; saturate in the case |
| where input is -2147483648 (0x8000 0000). |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| L_var1 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_negate(Word32 L_var1)
{
Word32 L_var_out;
L_var_out = (L_var1 == MIN_32) ? MAX_32 : -L_var1;
return(L_var_out);
}
/*___________________________________________________________________________
| |
| Function Name : mult_r |
| |
| Purpose : |
| |
| Same as mult with rounding, i.e.: |
| mult_r(var1,var2) = shr(((var1*var2) + 16384),15) and |
| mult_r(-32768,-32768) = 32767. |
| |
| Complexity weight : 2 |
| |
| Inputs : |
| |
| 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 : |
| |
| var_out |
| 16 bit short signed integer (Word16) whose value falls in the |
| range : 0xffff 8000 <= var_out <= 0x0000 7fff. |
|___________________________________________________________________________|
*/
Word16 mult_r(Word16 var1, Word16 var2)
{
Word16 var_out;
Word32 L_produit_arr;
L_produit_arr = (Word32)var1 * (Word32)var2; /* product */
L_produit_arr += (Word32) 0x00004000L; /* round */
L_produit_arr &= (Word32) 0xffff8000L;
L_produit_arr >>= 15; /* shift */
if (L_produit_arr & (Word32) 0x00010000L) {
/* sign extend when necessary */
L_produit_arr |= (Word32) 0xffff0000L;
}
var_out = sature(L_produit_arr);
return(var_out);
}
/*___________________________________________________________________________
| |
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