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Ti C62x DSP, help needed.

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Frosty_47

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Dear Komrades,

My failed attempts to learn TMS320C62 DSP from reference manuals brings me here. Due to absence of literature on this subject in book stores and local libraries, I need your help in understanding the following instruction:

ADDAH (.unit) src2, src1, dst
.unit= .D1 or .D2


The example in the Instruction Set Reference Guide (SPRU731) uses example on page 3-32, 3-33

texas instruments said:
ADDAH ; Add using Halfword Addressing Mode

ADDAH .D1X B14,42h,A4

before instruction
B14: 0020 1000h

1 cycle after instruction
A4: 0020 1084h

also, it says src2 + a src1 -> dst

wtf is a?
wtf is ucst5?
and how did that work? :confused:


Please keep this thread clean by replying within the context of this question.
 
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Frosty_47

New Member
I found a solution to my own problem on page 3-22 on (SPRU189e)

When in linear mod, src1 is left-shifted (it's value doubled) and than added with src2. The result is placed to specified destination.

When in circular mode, the contents of src1 are left shifted and added with src2. However, due to circular buffer configuration, the specified buffer size that is set by BK0 bit happens to be 8 bytes in the example (buffer size 2^(n+1) = 8 bytes). The left shifted value of 22 is 14 bytes larger than the buffer. From what I figured out, 14bytes gets rounded up to 16bytes. Than 116H - 10H (16) = 106H

Is there anyone that can explain why this is so?
 
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