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Altera_Forum
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14 years ago

NIOS2 HW & DIV Instructions + FPU

Hello i am in charge of designing a system that does a lot of complex sin/cos/* instructions and i need them to be fast. I am using NIOS2-F at 100mhz in a Cyclone IV. I've enabled HW and DIV ...
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Altera_Forum
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14 years ago

I will take a look into that, DSL why i get a worse performance when i add the float point unit custom instruction at NIOS2 @ QSys?

Doesnt make sense to me, NIOS2 already have those custom instructions built in?

Also what should i be looking for in the objdump? (Never used this command:eek:)

This is a part of my meter_run (main function) 


   4e0c:       39000017        ldw     r4,0(r7)
    4e10:       31800104        addi    r6,r6,4
    4e14:       10c7ff32        custom  252,r3,r2,r3
    4e18:       1105ff32        custom  252,r2,r2,r4
    4e1c:       40d1ff72        custom  253,r8,r8,r3
    4e20:       4893ffb2        custom  254,r9,r9,r2
    4e24:       39c00104        addi    r7,r7,4
    4e28:       29400904        addi    r5,r5,36
    4e2c:       32bff51e        bne     r6,r10,4e04 <meter_run+0xb4>
    4e30:       73800044        addi    r14,r14,1
    4e34:       5a400015        stw     r9,0(r11)
    4e38:       62000015        stw     r8,0(r12)
    4e3c:       6b400104        addi    r13,r13,4
    4e40:       63000104        addi    r12,r12,4
    4e44:       5ac00104        addi    r11,r11,4
    4e48:       73ffe31e        bne     r14,r15,4dd8 <meter_run+0x88>
    4e4c:       d8c00217        ldw     r3,8(sp)
    4e50:       d1e09117        ldw     r7,-32188(gp)
    4e54:       d2e09017        ldw     r11,-32192(gp)
    4e58:       d9000617        ldw     r4,24(sp)
    4e5c:       da400117        ldw     r9,4(sp)
    4e60:       da800517        ldw     r10,20(sp)
    4e64:       d9400317        ldw     r5,12(sp)
    4e68:       d2209317        ldw     r8,-32180(gp)
    4e6c:       d3209217        ldw     r12,-32184(gp)
    4e70:       1ac5ff32        custom  252,r2,r3,r11
    4e74:       d9800717        ldw     r6,28(sp)
    4e78:       19c7ff32        custom  252,r3,r3,r7
    4e7c:       1a47ff72        custom  253,r3,r3,r9
    4e80:       390fff32        custom  252,r7,r7,r4
    4e84:       1285ff72        custom  253,r2,r2,r10
    4e88:       22c9ff32        custom  252,r4,r4,r11
    4e8c:       1907ffb2        custom  254,r3,r3,r4
    4e90:       11c5ff72        custom  253,r2,r2,r7
    4e94:       2b09ff32        custom  252,r4,r5,r12
    4e98:       2a0bff32        custom  252,r5,r5,r8
    4e9c:       1947ff72        custom  253,r3,r3,r5
    4ea0:       1105ff72        custom  253,r2,r2,r4
    4ea4:       4191ff32        custom  252,r8,r8,r6
    4ea8:       330dff32        custom  252,r6,r6,r12
    4eac:       19a9ffb2        custom  254,r20,r3,r6
    4eb0:       1227ff72        custom  253,r19,r2,r8

I Guess it is using custom instructions right? (Even thought i didnt add the custom instruction guy @ QSys)