From mboxrd@z Thu Jan 1 00:00:00 1970 From: Luis R. Rodriguez Date: Mon, 29 Mar 2010 10:36:05 -0700 Subject: [ath9k-devel] query in ath9k In-Reply-To: <1aee2dca1003290358k41f23433k17783e4dbec57b41@mail.gmail.com> References: <1aee2dca1003290358k41f23433k17783e4dbec57b41@mail.gmail.com> Message-ID: <20100329173605.GC7643@tux> List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: ath9k-devel@lists.ath9k.org On Mon, Mar 29, 2010 at 03:58:37AM -0700, selvam wrote: > Hi all, > I have some queries in ath9k. > > In xmit.c, the variable 'bits_per_symbol' is used to store the number of bits per OFDM symbol for various data rates. > > static u32 bits_per_symbol[][2] = { > /* 20MHz 40MHz */ > { 26, 54 }, /* 0: BPSK */ > { 52, 108 }, /* 1: QPSK 1/2 */ > { 78, 162 }, /* 2: QPSK 3/4 */ > { 104, 216 }, /* 3: 16-QAM 1/2 */ > { 156, 324 }, /* 4: 16-QAM 3/4 */ > { 208, 432 }, /* 5: 64-QAM 2/3 */ > { 234, 486 }, /* 6: 64-QAM 3/4 */ > { 260, 540 }, /* 7: 64-QAM 5/6 */ > { 52, 108 }, /* 8: BPSK */ > { 104, 216 }, /* 9: QPSK 1/2 */ > { 156, 324 }, /* 10: QPSK 3/4 */ > { 208, 432 }, /* 11: 16-QAM 1/2 */ > { 312, 648 }, /* 12: 16-QAM 3/4 */ > { 416, 864 }, /* 13: 64-QAM 2/3 */ > { 468, 972 }, /* 14: 64-QAM 3/4 */ > { 520, 1080 }, /* 15: 64-QAM 5/6 */ > > > 1) Is it possible to keep only the values of MCS 0 to MCS 7 and calculate the rest on run time. so that we can save some amount of memory. > > For example, if MCS index is 8, then multiply the MCS 0 by 2, for MCS 9 mutiply MCS 1 by 2.. > > Can we use in that way?. Is there any performance tradeoff in terms of faster execution due to comparison? > > > 2) Why don't we use static u16 instead of static u32 to declare this variable? Is there any specific reason for using as u32? > > If my approach is improper, please excuse me. Try the patch and send it once tested and proved to work :) Luis