mpyi

This question is answered

Posted by omry cohen

on Aug 09 2012 03:15 AM

Prodigy110 points

im working with MSP430F2272

i run my program (on CC5) and after few minutes when i pause it

it gave me the message:

No source available for "_mpyi() at 0x88bc"

could some one tell why

All Replies

Posted by Mo.

on Aug 09 2012 03:48 AM

Genius11020 points

omry cohen
No source available for "_mpyi() at 0x88bc"

It seems that you have a multiplication in your code using the Hardware Multiplier support in CCS. Is that correct?

Can you provide this code?

BR,

Mo.

Posted by omry cohen

on Aug 09 2012 05:19 AM

Prodigy110 points

i didnt understand exactly what do tou mean by "using the Hardware Multiplier support in CCS".

Posted by Mo.

on Aug 09 2012 06:33 AM

Verified Answer

Verified by omry cohen

Genius11020 points

In the project properties, under Build -> MSP430 Linker -> Basic Options: "Link in hardware version of RTS mpy routine (--use_hw_mpy)". Here you have choices for the 16-bit or 32-bit multiplier, depending on your MSP430 variant.

From the command line, the replacement is invoked with the linker option '--use_hw_mpy[={16/32/F5}]'.

Using this, the compiler / linker makes use of the hardware multiplier whenever it sees a multiplication in your code. In the assembly code listing, you should see the set-up and then "CALLA #__mpyi_hw" for the call to the routine to use the hardware multiplier (with the correct routine for signed, unsigned, ....)

BR,

Mo.

Posted by omry cohen

on Aug 09 2012 06:58 AM

Prodigy110 points

THANKS

Posted by Jens-Michael Gross

on Aug 09 2012 11:27 AM

Guru141810 points

_mpyi() is a function that does an integer multiplication. It is part of the C runtime library (along with e.g. the startup code that initializes the variables in ram etc.)
It is automatically linked-in when the MSP has no hardware multiplier or if its use is disabled.
Since it comes form a library, the debugger has no source code for it.

Switch to assembly view and follow the code in single-steppign until it returns to your program code, where source is available. Most likely a multiplication.

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Posted by Arsen Norman

on Jan 30 2013 18:39 PM

Prodigy225 points

Hello.

I'm using H/W multiplier. Below are the sample C code, assembly output and dis-assembly step through.

The '__mpyi' actually jumps to a code that puts values in &MPY and &OP2 (per user guide) for h/w mutiplication.

#include "msp430x26x.h"
int x, y, z;
void main(void){
z = x * y;
}

main:
;* --------------------------------------------------------------------------*
   .dwcfi   cfa_offset, 4
   .dwcfi   save_reg_to_mem, 16, -4
;** 10   -----------------------    z = x*y;
   .dwpsn   file "../main.c",line 10,column 2,is_stmt
        MOV.W     &x+0,r12              ; [] |10|
        MOV.W     &y+0,r13              ; [] |10|
$C$DW$5   .dwtag DW_TAG_TI_branch
   .dwattr $C$DW$5, DW_AT_low_pc(0x00)
   .dwattr $C$DW$5, DW_AT_name("__mpyi")
   .dwattr $C$DW$5, DW_AT_TI_call
        CALLA     #__mpyi               ; [] |10|
                                          ; [] |10|
        MOV.W     r12,&z+0              ; [] |10|
;**     -----------------------    return;
   .dwpsn   file "../main.c",line 12,column 1,is_stmt
$C$DW$6   .dwtag DW_TAG_TI_branch
   .dwattr $C$DW$6, DW_AT_low_pc(0x00)
   .dwattr $C$DW$6, DW_AT_TI_return
        RETA      ; []
        ; []
   .dwattr $C$DW$4, DW_AT_TI_end_file("../main.c")
   .dwattr $C$DW$4, DW_AT_TI_end_line(0x0c)
   .dwattr $C$DW$4, DW_AT_TI_end_column(0x01)
   .dwendentry
   .dwendtag $C$DW$4

         __mpyi_hw:
0x03122:   1202                PUSH    ST
0x03124:   C232                DINT
0x03126:   4303                NOP
0x03128:   4C82 0130           MOV.W   R12,&Multiplier_MPY
0x0312C:   4D82 0138           MOV.W   R13,&Multiplier_OP2
0x03130:   421C 013A           MOV.W   &Multiplier_RESLO,R12
0x03134:   4132                POP.W   ST
0x03136:   0110                RETA
         main:
0x03138:   421C 1110           MOV.W   &x,R12
0x0313C:   421D 1112           MOV.W   &y,R13
0x03140:   13B0 3122           CALLA   #__mpyi_hw
0x03144:   4C82 1114           MOV.W   R12,&z
0x03148:   0110                RETA
         _system_pre_init:
0x0314A:   431C                MOV.W   #1,R12
0x0314C:   0110                RETA
         C$$EXIT, abort:
0x0314E:   4303                NOP
         C$L1:
0x03150:   3FFF                JMP     (C$L1)
         _nop:
0x03152:   0110                RETA