AIM -I Single Threaded-Code with Interrupts (data heap)H f1: 工1 pc addu… f2: 2 012 cli sti iret ih: ISR ￥2 ￥3 … (register file)R ie jf (code heap)c (state)s :=(H,R,ie) ::={f→I」* (program)P::=(c,s,pc)
AIM – I : Single Threaded-Code with Interrupts I1 f1: I2 f2: ih: ISR … (code heap) C 0 r1 1 2 … r2 r3 … rn (data heap) H (register file) R (state) S addu … cli sti iret … j f (program) P::=(C,S,pc) ::=(H,R,ie) ::={f I}* pc ie
Example:Teeter-Totter left right while(true){ 50 50 cli; timer: if([right]=0){ if([1eft]==0){ sti; print("right wins!"); break; iret; } [right]:=[right]-1; [left] :=[1eft]-1; [1eft]:=[1eft]+1; [right][right]+1; sti; iret; print("left wins！"); How to guarantee non-interference?
Example: Teeter-Totter while(true){ cli; if([right] == 0){ sti; break; } [right] := [right]-1; [left] := [left]+1; sti; } print(“left wins!”); timer: if([left] == 0){ print(“right wins!”); iret; } [left] := [left]-1; [right] := [right]+1; iret; 50 50 left right How to guarantee non-interference?