Quiz 6.3: Difference between revisions
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Sections start their location counters at zero. The .bss directives don't advance the counter, because they go off to a different section. Assembly instructions take up bytes of memory according to what they are and their addressing mode. Whenever a .sect happens the location counter is reset to zero. There is more in section 2 of this [http://www.ti.com/lit/ug/slau131m/slau131m.pdf TI Manual on the Assembler]. |
Sections start their location counters at zero. The .bss directives don't advance the counter, because they go off to a different section. Assembly instructions take up bytes of memory according to what they are and their addressing mode. Whenever a .sect happens the location counter is reset to zero. There is more in section 2 of this [http://www.ti.com/lit/ug/slau131m/slau131m.pdf TI Manual on the Assembler]. This quiz is more tailored to understanding the Assembly List file, that has a field for the location counter. Code Composer Studio doesn't generate this by default anymore. It is good to look at though. I wasn't able to correctly get the location counter values correct without the compiler's help. Fortunately you can still get it to make an assembly listing for you. |
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*0x0000 |
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[[File:assembly-listing-option.png]] |
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*0x0000 |
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*0x0000 |
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*0x0002 |
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*0x0008 |
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*0x000a |
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*0x000c |
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*0x000e |
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*0x000e |
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*0x0010 |
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*0x0002 |
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*0x0000 |
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*0x0000 |
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<nowiki>MSP430 Assembler Unix v15.12.3 Tue Nov 1 17:48:13 2016 |
<nowiki>MSP430 Assembler Unix v15.12.3 Tue Nov 1 17:48:13 2016 |
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Revision as of 16:59, 1 November 2016
Sections start their location counters at zero. The .bss directives don't advance the counter, because they go off to a different section. Assembly instructions take up bytes of memory according to what they are and their addressing mode. Whenever a .sect happens the location counter is reset to zero. There is more in section 2 of this TI Manual on the Assembler. This quiz is more tailored to understanding the Assembly List file, that has a field for the location counter. Code Composer Studio doesn't generate this by default anymore. It is good to look at though. I wasn't able to correctly get the location counter values correct without the compiler's help. Fortunately you can still get it to make an assembly listing for you.
You get the Assembly List file by going into the Build Settings->Build->Advanced Options->Assembler, and tick the Generate listing file box. Here is the listing file I got using the MSP430G2553 processor.
MSP430 Assembler Unix v15.12.3 Tue Nov 1 17:48:13 2016
Tools Copyright (c) 2003-2015 Texas Instruments Incorporated
../main.asm PAGE 1
1 .cdecls C,"msp430.h" ; include c header
2 000000 .bss cnt,2 ; WDT second counter
3 000002 .bss cat,4
4 000000 .text ; program section
5 000000 4031 start: mov.w #0x0400,SP ; set stack pointer
000002 0400
6 000004 40B2 mov.w #0x5a18,&WDTCTL ; set WD timer interval
000006 5A18
000008 0000!
7 00000a 40B2 mov.w #0x00fa,&cnt ; 1 sec WD counter
00000c 00FA
00000e 0000!
8 000010 43D2 mov.b #0x01,&IE1 ; enable WDT interrupt
000012 0000!
9 000014 D3D2 bis.b #0x01,&P1DIR ; P1.0 output
000016 0000!
10 000018 D032 bis.w #0x0018,SR ; enable interrupts
00001a 0018
11 000006 .bss dog,2
12 00001c E3D2 wdt_isr: xor.b #0x01,&P1OUT ; toggle P1.0
00001e 0000!
13 000020 1300 reti ; return from interrupt
14 000000 .sect ".int10" ; WDT vector section
15 000000 0000! .word wdt_isr ; Watchdog ISR
16 000000 .sect ".reset" ; PUC vector section
17 000000 0000! .word start ; RESET ISR
18 .end
No Assembly Errors, No Assembly Warnings
You can see that my guess wasn't right. The second column of numbers is the location counter. :-)