Cypress DCT-1D Podręcznik Użytkownika Pobierz pdf (Strona 68)

CHAPTER 6. LAB TASK 4 - CUSTOM INSTRUCTIONS

Code Name Explanation Stands Alone

0xF F C0 SOF

Start of frame for baseline coded pictures. No

0xF F E0 APP

Application speciﬁc data used by JFIF. No

0xF F DA SOS Start of s can. The image data starts after

this marker segment.

0xF F Dn RST

Restart marker n(n = 0, 1...7), restart de-

coding after this marker.

Yes

0xF F D9 EOI End of image, data after this marker is ig-

nored.

Yes

Table 6.3: Important JFIF markers

6.6 Important Files For this lab task

In addition to the ﬁles listed in section 4.4.1 also the following ﬁles are important.

• or1200_lsu.sv: Load Store Unit, the module used by the or1200 processor to

load/store from/to memory.

• or1200_defines.v: Deﬁnes for the or1200 RTL code, look for

‘ifdef OR1200_SBIT_IMPL

• or1200_vlx_top.sv: A skeleton top level module for the set bit instruction.

• or1200_ctrl.sv: The instruction decoder.

• or1200_sprs.sv: Special purpose register control.

• jchuff.c: Code dealing with the Huffman-encoding.

6.7 Tips and tricks

In this section we have collected some notes that you might ﬁnd useful.

• If you want to simulate the set bit instruction together with the rest of the system,

you will have to modify the monitor to run your test code right after the system

has started. See the directions in section 3.3.3 on how to modify the monitor.

• In order to improve the performance of the code you can remove some of the

performance counters. But all performance counters in jpegtest.c has to re-

main!

• How to write to a special purpose registers with address 0xC000 in C-code:

asm volatile("l.mtspr %0,%1,0x0" : : "r"(0xc000),"r"(value))

1 2 ... 63 64 65 66 67 68 69 70 71 72 73 ... 81 82

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Cypress DCT-1D Podręcznik Użytkownika Strona 68