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Altera_Forum
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10 years ago

how to use the floating point hardware in nios II custom instructions

hi i want to compare the speed difference of floating point calc between custom instruction floating point and software. this is my code:# include <stdio.h># include <altera_avalon_pio_regs....
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
10 years ago

1. <application_name>.objdump is a file found besides your <application_name>.elf file. It is a readable object file that gets translated from elf. It will shows you the exact code compiled.

To make sure that the floating point operations gets compiled, you should see something similar to below (for c=a*b operation):

Without floating point hardware, software emulation:

c=a*b;

2ac: d9000217 ldw r4,8(sp)

2b0: d9400117 ldw r5,4(sp)

2b4: 000031c0 call 31c <__mulsf3>

2b8: d8800015 stw r2,0(sp)

With floating point hardware:

c=a*b;

2ac: d8800217 ldw r2,8(sp)

2b0: d8c00117 ldw r3,4(sp)

2b4: 10c5ff32 custom 252,r2,r2,r3

2. do you know what is the optimization used? ie -O2 or -O0?