rpitx/csdr
1
0
Fork 0
Code Issues Pull requests Packages Projects Releases Wiki Activity

Fixed issue simonyiszk/csdr#15 by using veor instead of vmov to zero accumulators in fir_decimate_cc. Also removed some unused variables

Browse source
This commit is contained in:
Rico van Genugten 2016-10-06 09:12:34 +00:00
parent 8952449b09
commit 7ba726af5b
1 changed files with 3 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
libcsdr.c
View file

@ -280,11 +280,7 @@ int fir_decimate_cc(complexf *input, complexf *output, int input_size, int decim
for(int i=0; i<input_size; i+=decimation) //@fir_decimate_cc: outer loop
{
if(i+taps_length>input_size) break;
register float acci=0;
register float accq=0;
register int ti=0;
register float* pinput=(float*)&(input[i+ti]);
register float* pinput=(float*)&(input[i]);
register float* ptaps=taps;
register float* ptaps_end=taps+taps_length;
float quad_acciq [8];
@ -297,8 +293,8 @@ q4, q5: accumulator for I branch and Q branch (will be the output)
*/
asm volatile(
" vmov.f32 q4, #0.0\n\t" //another way to null the accumulators
" vmov.f32 q5, #0.0\n\t"
" veor q4, q4\n\t"
" veor q5, q5\n\t"
"for_fdccasm: vld2.32 {q0-q1}, [%[pinput]]!\n\t" //load q0 and q1 directly from the memory address stored in pinput, with interleaving (so that we get the I samples in q0 and the Q samples in q1), also increment the memory address in pinput (hence the "!" mark) //http://community.arm.com/groups/processors/blog/2010/03/17/coding-for-neon--part-1-load-and-stores
" vld1.32 {q2}, [%[ptaps]]!\n\t"
" vmla.f32 q4, q0, q2\n\t" //quad_acc_i += quad_input_i * quad_taps_1 //http://stackoverflow.com/questions/3240440/how-to-use-the-multiply-and-accumulate-intrinsics-in-arm-cortex-a8 //http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0489e/CIHEJBIE.html