nope... e: b2 40 b4 ff mov #-76, &0x0138 ;#0xffb4 12: 38 01 14: c2 43 39 01 mov.b #0, &0x0139 ;r3 As==00 check the third line... or the result of mult does not depend on high nibble of OP2 ? If there is a bug I'll fix this shortly.
~d On Wednesday 20 October 2004 15:20, dkorov...@luxoft.com wrote: > Dmitry, > Will you explain me the thing. ((unsigned int)180) treated as a one byte > variable? Why? Am I wrong in assumption that first wert should be > converted to unsigned int, next 180 must be converted to unsigned int > and at last multiplied. The result must be converted to unsigned int (no > idea, what for). > Am I right? > Regards, > Dmitriy Korovkin > > -----Original Message----- > From: mspgcc-users-ad...@lists.sourceforge.net > [mailto:mspgcc-users-ad...@lists.sourceforge.net] > Sent: Wednesday, October 20, 2004 2:16 PM > To: mspgcc-users@lists.sourceforge.net > Subject: Re: [Mspgcc-users] Something strange with multiplication of > constant byte numbers > > this is a feature actually:) > you forgot about operations order. > ~d > > On Wednesday 20 October 2004 12:48, Else Marcus wrote: > > Hello! > > > > There is something strange with multiplication of constant byte > > numbers. > > > ------------------------------------------------------------------------ > --- > > >- ------ > > Example 1.1: > > > > unsigned int multiplikation (unsigned char wert) > > { > > return (unsigned int)((unsigned int)wert*((unsigned int)180)); > > 0: 02 12 push r2 ; > > 2: 32 c2 dint > > 4: 03 43 nop > > 6: c2 4f 30 01 mov.b r15, &0x0130 ; > > a: c2 43 31 01 mov.b #0, &0x0131 ;r3 As==00 > > e: b2 40 b4 ff mov #-76, &0x0138 ;#0xffb4 > > 12: 38 01 > > 14: c2 43 39 01 mov.b #0, &0x0139 ;r3 As==00 > > 18: 1f 42 3a 01 mov &0x013a,r15 ;0x013a > > 1c: 32 41 pop r2 ; > > } > > 1e: 30 41 ret > > ------------------------------------------------------------------------ > --- > > >- ------ > > > > At line (e:) the high byte is set to 0xff. Because of the word access > > the > > > hardware multiplier will start and line (14:) has no effect. > > > > With storing the 180 in uiTemp the code is ok (Example 1.2). > > ------------------------------------------------------------------------ > --- > > >- ------ > > Example 1.2: > > > > unsigned int multiplikation (unsigned char wert) > > { > > unsigned int uiTemp = 180; > > return (unsigned int)((unsigned int)wert*(unsigned int)uiTemp); > > 0: 7f f3 and.b #-1, r15 ;r3 As==11 > > 2: 02 12 push r2 ; > > 4: 32 c2 dint > > 6: 03 43 nop > > 8: 82 4f 32 01 mov r15, &0x0132 ; > > c: b2 40 b4 00 mov #180, &0x0138 ;#0x00b4 > > 10: 38 01 > > 12: 1f 42 3a 01 mov &0x013a,r15 ;0x013a > > 16: 32 41 pop r2 ; > > } > > 18: 30 41 ret > > ------------------------------------------------------------------------ > --- > > >- ------ > > > > The next example uses adding and shifting for multiplikation. > > ------------------------------------------------------------------------ > --- > > >- ------ > > Example 2.1: > > > > unsigned int multiplikation (unsigned char wert) > > { > > return (unsigned int)((unsigned int)wert*((unsigned int)129)); > > 0: 4e 4f mov.b r15, r14 ; > > 2: 0e 5e rla r14 ; > > 4: 0e 5e rla r14 ; > > 6: 0e 5e rla r14 ; > > 8: 0e 5e rla r14 ; > > a: 0e 5e rla r14 ; > > c: 0e 5e rla r14 ; > > e: 0e 5e rla r14 ; > > 10: 7f f3 and.b #-1, r15 ;r3 As==11 > > 12: 0f 8e sub r14, r15 ; > > } > > 14: 30 41 ret > > ------------------------------------------------------------------------ > --- > > >- ------ > > The value to return ist wert - wert*128 and not wert + wert*128. > > > > With storing the 129 in uiTemp the code is ok again (Example 2.2). > > ------------------------------------------------------------------------ > --- > > >- ------ > > Example 2.2: > > > > unsigned int multiplikation (unsigned char wert) > > { > > unsigned int uiTemp = 129; > > return (unsigned int)((unsigned int)wert*(unsigned int)uiTemp); > > 0: 7f f3 and.b #-1, r15 ;r3 As==11 > > 2: 02 12 push r2 ; > > 4: 32 c2 dint > > 6: 03 43 nop > > 8: 82 4f 32 01 mov r15, &0x0132 ; > > c: b2 40 81 00 mov #129, &0x0138 ;#0x0081 > > 10: 38 01 > > 12: 1f 42 3a 01 mov &0x013a,r15 ;0x013a > > 16: 32 41 pop r2 ; > > } > > 18: 30 41 ret > > ------------------------------------------------------------------------ > --- > > >- ------ > > > > Used options for mspgcc: -x c -c -g -O2 -Wall -mmcu=msp430x147 > > > > Release: mspgcc-20040723.exe > > > > Is the different behavior between examples 1.1 and 1.2 and between 2.1 > > and > > > 2.2 a bug or a feature? > > Or is it my mistake? > > > > Marcus Else > > > > > > ------------------------------------------------------- > > This SF.net email is sponsored by: IT Product Guide on > > ITManagersJournal > > > Use IT products in your business? Tell us what you think of them. Give > > us > > > Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out > > more > > > http://productguide.itmanagersjournal.com/guidepromo.tmpl > > _______________________________________________ > > Mspgcc-users mailing list > > Mspgcc-users@lists.sourceforge.net > > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > > ------------------------------------------------------- > This SF.net email is sponsored by: IT Product Guide on ITManagersJournal > Use IT products in your business? Tell us what you think of them. Give > us > Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out > more > http://productguide.itmanagersjournal.com/guidepromo.tmpl > _______________________________________________ > Mspgcc-users mailing list > Mspgcc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mspgcc-users > > > > ------------------------------------------------------- > This SF.net email is sponsored by: IT Product Guide on ITManagersJournal > Use IT products in your business? Tell us what you think of them. Give us > Your Opinions, Get Free ThinkGeek Gift Certificates! Click to find out more > http://productguide.itmanagersjournal.com/guidepromo.tmpl > _______________________________________________ > Mspgcc-users mailing list > Mspgcc-users@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/mspgcc-users
