Messages in this thread | | | Date | Fri, 10 Mar 2006 10:03:58 -0800 | From | Carlos Munoz <> | Subject | Re: How can I link the kernel with libgcc ? |
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Denis Vlasenko wrote:
>On Friday 10 March 2006 05:47, Carlos Munoz wrote: > > >>Lee Revell wrote: >> >> >> >>>On Thu, 2006-03-09 at 19:25 -0800, Carlos Munoz wrote: >>> >>> >>> >>> >>>>I figured out how to get the driver to use floating point operations. >>>>I included source code (from an open source math library) for the >>>>log10 function in the driver. Then I added the following lines to the >>>>file arch/sh/kernel/sh_ksyms.c: >>>> >>>> >>>> >>>> >>>Where is the source code to your driver? >>> >>>Lee >>> >>> >>> >>> >>> >>Hi Lee, >> >>Be warned. This driver is in the early stages of development. There is >>still a lot of work that needs to be done (interrupt, dma, etc, etc). >> >> > >What? You are using log10 only twice! > > if (!(siu_obj_status & ST_OPEN)) { > ... > /* = log2(over) */ > ydef[22] = (u_int32_t)(log10((double)(over & 0x0000003f)) / > log10(2)); > ... > } > else { > ... > if (coef) { > ydef[16] = 0x03045000 | (over << 26) | (tap - 4); > ydef[17] = (tap * 2 + 1); > /* = log2(over) */ > ydef[22] = (u_int32_t) > (log10((double)(over & 0x0000003f)) / log10(2)); > } > >Don't you think that log10((double)(over & 0x0000003f)) / log10(2) >can have only 64 different values depending on the result of (over & 0x3f)? > >Obtain them from precomputed uint32_t log10table[64]. >-- >vda > > Hi Denis,
Yes, the driver code so far only uses log10 twice, but there will be more uses for it as I populate the rest of the tables. However, I think its use will be some what limited. I wasn't aware that the floating point registers are not saved. I'll investigate a way to create a table with pre-calculated log10 values.
Thanks,
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