Assembly Exercise Analyze the following lines of code. Refer to Two's Complement and Fractional Arithmetic for 16-bit Processors, Addressing Modes for TI TMS320C55x, and the Mnemonic Instruction Set manual for help.

Anything following a ";" is considered a comment. In this case, the comments indicate the contents of the auxiliary registers, the BK03 register, and the address registers before the execution of the first instruction, mov. The line FIR_len .set 3 defines the name FIR_len as equal to 3. The BK03 register contains the length of the circular buffer we want to use for auxiliary register 0 through 3. The BSET AR3LC modifies the increment operator + so that it behaves as a circular buffer. This means circular addressing will be used for AR3. Refer to Section 6.11 of the CPU Reference Guide for help on circular addressing. Note that any number followed by an "h" or preceded with a 0x represents a hexadecimal value. 1000h and 0x1000 both refer to the decimal number 4096. Assume that the data memory is initialized as follows starting at location 1000h.

Data Memory Assignment (before execution) Memory location Value 1000h 1000h 1001h 0000h 1002h 4000h 1004h 1000h 1005h 1000h 1006h 4000h 1007h 1000h 1008h 0000h

Data Memory Assignment (before execution) After familiarizing yourself with the mov, rpt, and macm instructions, step through each line of code and record the values of the accumulator AC0 and auxiliary registers AR2 and AR3 in the spaces provided in . Additionally, record the value of the memory contents after all three instructions have been "executed" in the blank data memory table in .

AC0 AR2 AR3 00 0000 8000h 1000h 1004h at start of code after mov instruction line 11 after mov instruction line 12 after mov instruction line 13 after mov instruction line 14 after mov instruction line 15 after rpt instruction line 16 after first macm instruction after second macm instruction after third macm instruction

Execution Results When working through the exercise, take into account that the accumulator AC0 is a 40-bit register, and that the multiplier is in the fractional arithmetic mode. In this mode, integers on the DSP are interpreted as fractions, and the multiplier will treat them accordingly. This is done by shifting the result of the integer multiplier in the ALU left one bit. (All the arithmetic is fractional in these examples.) Multiplies performed by the ALU (via the macm instruction) produce a result that is twice what you would expect if you just multiplied the two integers together. DSP numerical representation and arithmetic are described further in Two's Complement and Fractional Arithmetic for 16-bit Processors.

Data Memory Assignment (after execution) Memory location Value 1000h 1001h 1002h 1004h 1005h 1006h 1007h 1008h

Data Memory Assignment (after execution)