| ??? 04/15/05 16:24 Read: times |
#91664 - table lookup Responding to: ???'s previous message |
My best table lookup routine was 20 cycles including ret. This required a 4*3*256 byte table (3kB) aligned at 256 byte boundary; plus some space for code; and destroys dptr.
To reduce tables, the case of the highest two bits are zero can be solved separately (using mul ab, this branch executes in 15 cycles including ret). This requires 3*3*256 byte table (2.something kB) but 2 more cycles (=22) this is 3.7us, is it too much? Still I think you can try to spare elsewhere. Jan Waclawek |
| Topic | Author | Date |
| Fast Square. | 01/01/70 00:00 | |
| Square dancing | 01/01/70 00:00 | |
| table lookup??? | 01/01/70 00:00 | |
| code & algorithm | 01/01/70 00:00 | |
| 16*16 bit is slower than what I want. | 01/01/70 00:00 | |
| How fast? | 01/01/70 00:00 | |
| Re: How Fast | 01/01/70 00:00 | |
| ... probably impossible in 15 cycles | 01/01/70 00:00 | |
| why cycles ? | 01/01/70 00:00 | |
| Re: Microseconds | 01/01/70 00:00 | |
| table lookup | 01/01/70 00:00 | |
| Natsemi appnote or CORDIC | 01/01/70 00:00 | |
| Natsemi link to appnote | 01/01/70 00:00 | |
| (a+b)^2=a^2+2*a*b+b^2 | 01/01/70 00:00 | |
| Thats Slow. | 01/01/70 00:00 | |
| faster need hardware | 01/01/70 00:00 | |
| How fast do you need? | 01/01/70 00:00 | |
| Re: How Fast. | 01/01/70 00:00 | |
| Just? | 01/01/70 00:00 | |
| Incorrect | 01/01/70 00:00 | |
| Correct? | 01/01/70 00:00 | |
| Whooooopa... Sorry. | 01/01/70 00:00 | |
| Thanks | 01/01/70 00:00 | |
| I tried... | 01/01/70 00:00 | |
| optimum? table driven | 01/01/70 00:00 | |
| Jan metod | 01/01/70 00:00 | |
| Hardware? | 01/01/70 00:00 | |
| CPLD? | 01/01/70 00:00 | |
| SILabs f12x does it in hardware | 01/01/70 00:00 | |
| Re: SiLabs F12x | 01/01/70 00:00 | |
| Price | 01/01/70 00:00 | |
| F12x price | 01/01/70 00:00 | |
| F12x MAC | 01/01/70 00:00 | |
| provided in the datasheet | 01/01/70 00:00 | |
| Just out of interest | 01/01/70 00:00 | |
| clarification | 01/01/70 00:00 | |
| CPLD? | 01/01/70 00:00 | |
| too expensive | 01/01/70 00:00 | |
| Absolute rubbish Oleg | 01/01/70 00:00 | |
| explain | 01/01/70 00:00 | |
| your right | 01/01/70 00:00 | |
| especially for those... | 01/01/70 00:00 | |
| I need to say this.... | 01/01/70 00:00 | |
| By the way..... | 01/01/70 00:00 | |
| just a demo | 01/01/70 00:00 | |
| Hang on. | 01/01/70 00:00 | |
| Oh bollocks | 01/01/70 00:00 | |
| Well oleg | 01/01/70 00:00 | |
| Please check my answer. | 01/01/70 00:00 | |
| Here you go | 01/01/70 00:00 | |
| You're having me on. | 01/01/70 00:00 | |
| Pascal? | 01/01/70 00:00 | |
| Pascal? | 01/01/70 00:00 | |
| Why ? | 01/01/70 00:00 | |
| It was changed because,,, | 01/01/70 00:00 | |
| Its because | 01/01/70 00:00 | |
| For Jez | 01/01/70 00:00 | |
| For Michael | 01/01/70 00:00 | |
| simulation | 01/01/70 00:00 | |
| Re: Fast Square | 01/01/70 00:00 | |
| Prahlad, waithing for a conclusion | 01/01/70 00:00 | |
| just an exercise... | 01/01/70 00:00 | |
| Tricky | 01/01/70 00:00 | |
| Jez asked his cat, I asked my sheep | 01/01/70 00:00 | |
| Conclusion. | 01/01/70 00:00 | |
SPI EEPROM | 01/01/70 00:00 |