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-- HASM Example File
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.equ fpgabase      0xa0000000;
.equ membase       0x80000000;
.equ memfaultcount 0xa0000010;

.isr isr_handler;



start:  
   call mem_test;


stophere:
    jmp stophere;
   



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-- mem_test shows how to implement a simple memory
-- test in hasm.
---------------------------------------------------
mem_test:
   ld rega,membase;         -- Base address of memory
   ld regc,0x0;             -- Loop count
mem_write: 

   ld regb,0x5a5a5a5a;      -- Test pattern A
   wr rega,regb;            -- Write rega to address pointed to by regb   
   add rega,0x04;           -- Bump mem pointer

   ld regb,0xa5a5a5a5;      -- Test pattern B
   wr rega,regb;            -- Write rega to address pointed to by regb
   add rega,0x04;           -- Bump mem pointer

   add regc,0x01;           -- Bump loop count
   cmp_e regc,0x100;        -- Done writing?
   jmp mem_write;           -- No, keep going

   ld rega,membase;         -- Finished writing so reinit for a read
   ld regc,0x0;             -- Reinit the loop pointer
mem_verify:
   rd regb,rega;            -- Read back first location
   cmp_e regb,0x5a5a5a5a;   -- First value ok?
   call mem_fault;          -- Values didn't match so call fault handler
   add rega,0x4;            -- Bump the address pointer
   rd regb,rega;            -- Get the next value
   cmp_e regb,0xa5a5a5a5;   -- Check against second patter
   call mem_fault;          -- Didn't match, call the handler
   add regc,0x1;            -- Bump the iteration count
   cmp_e regc,0x100;        -- Done yet?
   jmp mem_verify;          -- No, keep going
   ret;                     -- Yep return



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-- mem_fault is responsible for incrementing the
-- fault count stored in the FPGA.
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mem_fault:
   push rega;               -- Save rega
   rd rega,memfaultcount;   -- Get the fault count
   add rega,0x1;            -- Increment the fault count
   wr rega,memfaultcount;   -- Write the fault count back
   pop rega;                -- Restore rega
   ret;                     -- Return to caller

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-- isr_handler gets called when then the 
-- machine_interrupt input to the cycle_simulator 
-- file is brought high. 
---------------------------------------------------
isr_handler:
   push regd;
   pop regd;
   ret;