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I am using an 8051 (C51/BL51) with no off-chip memory. I have two functions with parameters:
void Detect( U8 iLed )
and
static U8 INHSampleHandler( U16 u16Sample )
Now I understand that Keil will allocate a variable (in DATA) for these. The problem seems to be that the locator is using the same memory location for both. I cannot understand why.
Below are excerpts from the scratchpad showing 2 "D:0026H". These are the only places these symbols are declared. Any ideas what I'm doing wrong?
Thanks, Jeff
BL51 BANKED LINKER/LOCATER V5.12 07/14/2011 09:36:23 PAGE 1 BL51 BANKED LINKER/LOCATER V5.12, INVOKED BY: Z:\TOOLS\SOFTWARE\KEIL\BL51.EXE Z:\Software\FB_CPU_Init.obj, >> Z:\Software\Settings.obj, Z:\Software\Glo >> bals.obj, Z:\Software\Devices\Clock.obj, Z:\ >> Software\Devices\Flash.obj, Z:\Software\Devices\HMI.obj >> , Z:\Software\Devices\INH.obj, Z:\ >> Software\Devices\ADC.obj, Z:\Software\Devices\Timer.obj, Z >> :\Software\Builds\TestINH - 06-00039-21-09\Main.obj >> , Z:\Software\Test\Test_Button.obj, Z:\So >> ftware\Builds\TestINH - 06-00039-21-09\Version.obj TO Z:\ >> Software\Builds\TestINH - 06-00039-21-09\06-00039-21-09-xx.wsp >> RS (256) PL (68) PW (78) XDATA (?XD?SETTINGS (0X0)) CODE (?CO?VERSION (0X7 >> FC0)) MEMORY MODEL: SMALL Deleted for brevity ------- PROC _INHSAMPLEHANDLER D:0026H SYMBOL u16Sample C:0BF1H LINE# 150 C:0BF5H LINE# 151 C:0BF5H LINE# 207 C:0BF7H LINE# 208 ------- ENDPROC _INHSAMPLEHANDLER ------- ENDMOD INH Deleted for brevity C:09FEH PUBLIC _Detect C:074EH PUBLIC main ------- PROC _DETECT D:0026H SYMBOL iLed
Having mocked you of having less curiosity than me, I could hardly ignore your request. (I had to change your header files as I don't have those - I'm using an 8051F930 - so perhaps it's not an apples-apples comparison.)
With optimization 4+ var1/var2 are at the same address. However the actual assembler code doesn't reference these and uses registers. Not a fair test.
With optimization at 2, var1/var2 do not overlay each other. I would not expect this program to write anything other than 36 to P2.
I have to change the code as follows to get the data to overlay:
static void (*mHandler)(unsigned int uData); void sub1(unsigned char var1) { var1=0; //reset var1/var2 if (var1) var1=0; //make sure var1 is always 0 //P2=var1; //make sure tmr0 is working } void sub2(unsigned char var2) { var2=var2+1; //increment var1/var2 if (var2==0) var2=1; //make sure var2 is never zero NOP256(); NOP256(); //delay 512 ticks - create opportunity for tmr0 to fire at least once P2=var2; //output var2 on P0 if ( var2 == 0 ) { P2 = 1; } } void tmr0_isr(void) interrupt 1 { // sub1(0); (*mHandler)(0); //call sub1 periodically to reset var1/var2 } int main(void) { mHandler = sub1; TR0=0; //turn off tmr0 TMOD = (TMOD & 0xf0) | 0x02; //tmr0 in mode 2 (auto reload tl0 with th0 TH0=-100; //tmr strikes every 100 ticks TL0=TH0; ET0=1; //enable tmr0 interrupt TR0=1; //turn on tmr0 EA=1; //enable global interrupt while (1) { sub2(35); } }
This code seems to suffer from the same problem as my program. In fact, from within Sub2 I got var2 == 0.
"This code seems to suffer from the same problem as my program. In fact, from within Sub2 I got var2 == 0."
if you really had curiosity, you probably would have run it on different platforms and observed the differences in behavior and asked yourself why.
I actually claimed to have a lack of curiosity - and proud of it.
Thanks to everyone here to for their contributions to a case solved. Especially to Ron who, strangely enough, found the solution but didn't recommend it.