24-bit integers would have to be 16-bit aligned for the cpu to be able to load them efficiently, those negating any storage benefits. So to be able to store them efficiently, you would effectively have a struct containing three 8-bit bytes (or an array of three bytes). I think the best you could do here is to make a C++ class containing these three bytes, with conversion operations to and from int20_t types. It should be possible to do this with code that is almost as efficient as a real gcc implementation.
mvh., David On 05/06/13 16:09, Peter Bigot wrote: > Best to submit this to the gcc project; it's certainly not something that > would be added through mspgcc. > > int20_t was an enhancement I thought useful since the MSP430 CPUX > architecture enables it, but I don't have reason to believe other MSP430 > toolchains (including the upcoming RH GCC) will recognize it. Native > support for it on CPUX still requires 32-bits when it's written to memory, > though, and that wouldn't change since its inherent in the way the > instruction set works. > > Peter > > > On Wed, Jun 5, 2013 at 8:53 AM, kuldeep dhaka <kuldeepdha...@gmail.com>wrote: > >> while working on a program i faced a problem. >> i need only 20 bit , and having a 32 bit only waste more memory(12 byte), >> 24bit would much be better. >> i need a uint24_t variable but gcc dont support it so i have to start with >> uint32_t. >> it would be very nice if gcc support such variables. >> i tried a little program and found that gcc (on i686) dont support it. >> >> http://embeddedgurus.com/stack-overflow/2009/06/three-byte-integers/ >> ------------------------------------------------------------------------------ How ServiceNow helps IT people transform IT departments: 1. A cloud service to automate IT design, transition and operations 2. Dashboards that offer high-level views of enterprise services 3. A single system of record for all IT processes http://p.sf.net/sfu/servicenow-d2d-j _______________________________________________ Mspgcc-users mailing list Mspgcc-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mspgcc-users
