laiyp/lib_xua
1
0
Fork 0
forked from PAWPAW-Mirror/lib_xua
Code Pull Requests Activity

added toplevel makefile for xpd

Browse Source
This commit is contained in:
dan
2014-01-22 11:00:41 +00:00
parent 7c42307440
commit 98b3bdba95
47 changed files with 2789 additions and 2778 deletions
Download Patch File Download Diff File Expand all files Collapse all files

26
module_usb_audio/endpoint0/dbcalc.xc
View File

@@ -21,7 +21,7 @@ static unsigned coef[14] = {2407, 13778, 64588, 308051, 1346110, 5261991, 182775
Parameters:
db - The db value to convert.
db_frac_bits - The number of binary fractional bits in the supplied decibel value
db_frac_bits - The number of binary fractional bits in the supplied decibel value
result_frac_bits - The number of required fractional bits in the result.
Returns:
@@ -37,24 +37,24 @@ unsigned db_to_mult(int db, int db_frac_bits, int result_frac_bits)
unsigned mask = ~((1<<DB_CALC_PREC)-1);
/* Make sure we get 0db bang on */
if (db == 0)
if (db == 0)
return (1 << result_frac_bits);
/* First scale the decibal value to the required precision and divide by 10
/* First scale the decibal value to the required precision and divide by 10
We scale to DB_CALC_PREC - 4 before the division with to make sure we don't overflow */
db = db << (DB_CALC_PREC - 4 - 1 - db_frac_bits);
db = db / 10;
db = db << 4;
/* Extract the integer part of the exponent and calculate the integer power */
/* This could have been done a bit more efficiently by extracting the largest multiple log_10(2)
and then calculating a power of 2 (with the polynomial calc in the range [-log_10(2),log_10(2)].
/* This could have been done a bit more efficiently by extracting the largest multiple log_10(2)
and then calculating a power of 2 (with the polynomial calc in the range [-log_10(2),log_10(2)].
But we have something that works here and ultra-fast performance is not a requirement */
if (db < 0) {
intpart = ((-db) & mask);
db = db + intpart;
db = db + intpart;
intpart = intpart >> DB_CALC_PREC;
if (intpart) {
@@ -65,7 +65,7 @@ unsigned db_to_mult(int db, int db_frac_bits, int result_frac_bits)
}
else {
intpart = (db & mask);
db = db - intpart;
db = db - intpart;
intpart = intpart >> DB_CALC_PREC;
if (intpart) {
val0 = 1 << DB_CALC_PREC;
@@ -86,20 +86,20 @@ unsigned db_to_mult(int db, int db_frac_bits, int result_frac_bits)
val = (hi << (32-DB_CALC_PREC)) | (lo >> DB_CALC_PREC);
val += coef[i] >> (COEF_PREC - DB_CALC_PREC);
}
/* Finally multiply by the integer power (if there was an integer part) */
if (val0) {
int hi=0;
unsigned lo=0;
{hi, lo} = macs(val0,val,hi,lo);
val = (hi << (32-DB_CALC_PREC)) | (lo >> DB_CALC_PREC);
val = (hi << (32-DB_CALC_PREC)) | (lo >> DB_CALC_PREC);
}
/* We now have the result, just need to scale it to the required precision */
ret = val;
if (result_frac_bits > DB_CALC_PREC) {
return ret<<(result_frac_bits-DB_CALC_PREC);
}
@@ -113,7 +113,7 @@ unsigned db_to_mult(int db, int db_frac_bits, int result_frac_bits)
int main() {
/* Check that we don't overflow up to 9db
/* Check that we don't overflow up to 9db
Should give a value just under 0x80000 */
printhexln(db_to_mult(9,0,16));