Forum Discussion

Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
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

i check the system.h

and i find this:

/*

* Custom instruction macros

*

*/

# define ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0(n,A,B) __builtin_custom_inii(ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0_N+(n&ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0_N_MASK),(A),(B))

# define ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0_N 0xfc

# define ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0_N_MASK ((1<<2)-1)

i also tried

c=ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0(3,a,b);

c=ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0(1,a,b);

c=ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0(2,b,a);

c=ALT_CI_NIOS_CUSTOM_INSTR_FLOATING_POINT_0(0,b,a)

but the result is 0.0