16.1.9 MACC_PA

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The MACC_PA macro implements multiplication, multiply-add, and multiply-accumulate functions. The MACC_PA block can accumulate the current multiplication product with a previous result, a constant, a dynamic value, or a result from another MACC_PA block. Each MACC_PA block can also be configured to perform a Dot-product operation. All the signals of the MACC_PA block have optional registers.

16.1.9.1 Features

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The main features of the MACC_PA block are as follows:

Native 18 x 18 signed multiplication and supports 17 x 17 unsigned multiplication.
Independent third input C of data width 48 bits along with a CARRYIN, optionally registered.
Pre-adder of B with an independent fourth input D of data width 18 bits, optionally registered.
Internal cascade signals (48-bit CDIN and CDOUT) enable cascading of the Math blocks to support larger accumulator, adder, and subtracter without extra logic.
Normal addition/subtraction: CARRYIN + C[47:0] + E[47:0] ± { ( B[17:0] ± D[17:0]) x A[17:0] }.
Dot product mode: (B[8:0] ± D[8:0]) x A[17:9] ± (B[17:9] ± D[17:9]) x A[8:0].
SIMD mode for dual independent multiplication of two pairs of 9-bit operands.
Supports both registered and unregistered inputs and outputs.
Arithmetic right-shift by 17 bits of the loopback of CDIN.

The following figure shows a simplified block diagram of the MACC_PA block.

Figure 16-69. Simplified Block Diagram of MACC_PA

Table 16-141. MACC_PA Pin Descriptions
Port Name	Direction	Type	Polarity	Description
DOTP	Input	Static	High	Dot-product mode. When DOTP = 1, MACC_PA block performs Dot- product of two pairs of 9-bit operands. SIMD must not be 1. C[8:0] must be connected to CARRYIN.
SIMD	Input	Static	High	SIMD mode. When SIMD = 1, MACC_PA block performs dual independent multiplication of two pairs of 9-bit operands. DOTP must not be 1. ARSHFT17 must be 0. D[8:0] must be 0. C[17:0] must be 0. E[17:0] must be 0. Refer to Table 16-142 to see how operand E is obtained from P, CDIN or 0.
OVFL_CARRYOUT_SEL	Input	Static	High	Generate OVERFLOW or CARRYOUT with result P. OVERFLOW when OVFL_CARRYOUT_SEL = 0 CARRYOUT when OVFL_CARRYOUT_SEL = 1
CLK	Input	Dynamic	Rising edge	Clock for A, B, C, CARRYIN, D, P, OVFL_CARRYOUT, ARSHFT17, CDIN_FDBK_SEL, PASUB and SUB registers.
AL_N	Input	Dynamic	Low	Asynchronous load for A, B, P, OVFL_CARRYOUT, ARSHFT17, CDIN_FDBK_SEL, PASUB and SUB registers. Connect to 1, if none are registered. When asserted, A, B, P and OVFL_CARRYOUT registers are loaded with zero, while the ARSHFT17, CDIN_FDBK_SEL, PASUB and SUB registers are loaded with the complementary. value of the respective _AD_N.
A[17:0]	Input	Dynamic	High	Input data A.
A_BYPASS	Input	Static	High	Bypass data A registers. Connect to 1, if not registered. See Table 16-146.
A_SRST_N	Input	Dynamic	Low	Synchronous reset for data A registers. Connect to 1, if not registered. See Table 16-146.
A_EN	Input	Dynamic	High	Enable for data A registers. Connect to 1, if not registered. See Table 16-146.
B[17:0]	Input	Dynamic	High	Input data B to Pre-adder with data D.
B_BYPASS	Input	Static	High	Bypass data B registers. Connect to 1, if not registered. See Table 16-146.
B_SRST_N	Input	Dynamic	Low	Synchronous reset for data B registers. Connect to 1, if not registered. See Table 16-146.
B_EN	Input	Dynamic	High	Enable for data B registers. Connect to 1, if not registered. See Table 16-146.
D[17:0]	Input	Dynamic	High	Input data D to Pre-adder with data B. When SIMD = 1, connect D[8:0] to 0.
D_BYPASS	Input	Static	High	Bypass data D registers. Connect to 1, if not registered. See Table 16-147.
D_ARST_N	Input	Dynamic	Low	Asynchronous reset for data D registers. Connect to 1, if not registered. See Table 16-147.
D_SRST_N	Input	Dynamic	Low	Synchronous reset for data D registers. Connect to 1, if not registered. See Table 16-147.
D_EN	Input	Dynamic	High	Enable for data D registers. Connect to 1, if not registered. See Table 16-147.
CARRYIN	Input	Dynamic	High	CARRYIN for input data C.
C[47:0]	Input	Dynamic	High	Input data C. When DOTP = 1, connect C[8:0] to CARRYIN. When SIMD = 1, connect C[8:0] to 0.
C_BYPASS	Input	Static	High	Bypass CARRYIN and C registers. Connect to 1, if not registered. See Table 16-147.
C_ARST_N	Input	Dynamic	Low	Asynchronous reset for CARRYIN and C registers. Connect to 1, if not registered. See Table 16-147.
C_SRST_N	Input	Dynamic	Low	Synchronous reset for CARRYIN and C registers. Connect to 1, if not registered. See Table 16-147.
C_EN	Input	Dynamic	High	Enable for CARRYIN and C registers. Connect to 1, if not registered. See Table 16-147.
CDIN[47:0]	Input	Cascade	High	Cascaded input for operand E. The entire bus must be driven by an entire CDOUT of another MACC_PA or MACC_PA_BC_ROM block. In Dot-product mode, the driving CDOUT must also be generated by a MACC_PA or MACC_PA_BC_ROM block in Dot-product mode. Refer to Table 16-142 to see how CDIN is propagated to operand E.
P[47:0]	Output	—	High	Result data. See Table 16-143.
OVFL_CARRYOUT	Output	—	High	OVERFLOW or CARRYOUT. See Table 16-144.
P_BYPASS	Input	Static	High	Bypass P and OVFL_CARRYOUT registers. Connect to 1, if not registered. See Table 16-146. P_BYPASS must be 0 when CDIN_FDBK_SEL[0] = 1. See Table 16-142.
P_SRST_N	Input	Dynamic	Low	Synchronous reset for P and OVFL_CARRYOUT registers. Connect to 1, if not registered. See Table 16-146.
P_EN	Input	Dynamic	High	Enable for P and OVFL_CARRYOUT registers. Connect to 1, if not registered. See Table 16-146.
CDOUT[47:0]	Output	Cascade	High	Cascade output of result P. See Table 16-143. Value of CDOUT is the same as P. The entire bus must either be dangling or drive an entire CDIN of another MACC_PA or MACC_PA_BC_ROM block in cascaded mode.
PASUB	Input	Dynamic	High	Subtract operation for Pre-adder of B and D.
PASUB_BYPASS	Input	Static	High	Bypass PASUB register. Connect to 1, if not registered. See Table 16-145.
PASUB_AD_N	Input	Static	Low	Asynchronous load data for PASUB register. See Table 16-145.
PASUB_SL_N	Input	Dynamic	Low	Synchronous load for PASUB register. Connect to 1, if not registered. See Table 16-145.
PASUB_SD_N	Input	Static	Low	Synchronous load data for PASUB register. See Table 16-145.
PASUB_EN	Input	Dynamic	High	Enable for PASUB register. Connect to 1, if not registered. See Table 16-145.
CDIN_FDBK_SEL[1:0]	Input	Dynamic	High	Select CDIN, P or 0 for operand E. See Table 16-142.
CDIN_FDBK_SEL_BYPASS	Input	Static	High	Bypass CDIN_FDBK_SEL register. Connect to 1, if not registered. See Table 16-145.
CDIN_FDBK_SEL_AD_N[1:0] [1:0]	Input	Static	Low	Asynchronous load data for CDIN_FDBK_SEL register. See Table 16-145.
CDIN_FDBK_SEL_SL_N	Input	Dynamic	Low	Synchronous load for CDIN_FDBK_SEL register. Connect to 1, if not registered. See Table 16-145.
CDIN_FDBK_SEL_SD_N[1:0] [1:0] CDIN_FDBK_SEL_SD_N [1:0]	Input	Static	Low	Synchronous load data for CDIN_FDBK_SEL register. See Table 16-145.
CDIN_FDBK_SEL_EN	Input	Dynamic	High	Enable for CDIN_FDBK_SEL register. Connect to 1, if not registered. See Table 16-145.
ARSHFT17	Input	Dynamic	High	Arithmetic right-shift for operand E. When asserted, a 17-bit arithmetic right-shift is performed on operand E. Refer to Table 16-142 to see how operand E is obtained from P, CDIN or 0. When SIMD = 1, ARSHFT17 must be 0.
ARSHFT17_BYPASS	Input	Static	High	Bypass ARSHFT17 register. Connect to 1, if not registered. See Table 16-145.
ARSHFT17_AD_N	Input	Static	Low	Asynchronous load data for ARSHFT17 register. See Table 16-145.
ARSHFT17_SL_N	Input	Dynamic	Low	Synchronous load for ARSHFT17 register. Connect to 1, if not registered. See Table 16-145.
ARSHFT17_SD_N	Input	Static	Low	Synchronous load data for ARSHFT17 register. See Table 16-145.
ARSHFT17_EN	Input	Dynamic	High	Enable for ARSHFT17 register. Connect to 1, if not registered. See Table 16-145.
SUB	Input	Dynamic	High	Subtract operation.
SUB_BYPASS	Input	Static	High	Bypass SUB register. Connect to 1, if not registered. See Table 16-145.
SUB_AD_N	Input	Static	Low	Asynchronous load data for SUB register. See Table 16-145
SUB_SL_N	Input	Dynamic	Low	Synchronous load for SUB register. Connect to 1, if not registered. See Table 16-145.
SUB_SD_N	Input	Static	Low	Synchronous load data for SUB register. See Table 16-145.
SUB_EN	Input	Dynamic	High	Enable for SUB register. Connect to 1, if not registered. See Table 16-145.

Tip: Static inputs are defined at design time and need to be tied to 0 or 1.

Table 16-142. Truth Table—Propagating Data to Operand E
CDIN_FDBK_SEL[1]	CDIN_FDBK_SEL[0]	ARSHFT17	Operand E
0	0	X	48'b0
0	1	0	P[47:0]
0	1	1	{{17{P[47]}},P[47:17]}
1	X	0	CDIN[47:0]
1	X	1	{{17{CDIN[47]}},CDIN[47:17]}

Table 16-143. Truth Table—Computation of Result P and CDOUT
SIMD	DOTP	SUB	PASUB	Result P and CDOUT
0	0	0	0	CARRYIN + C[47:0] + E[47:0] + { (B[17:0] + D[17:0]) x A[17:0] }
0	0	0	1	CARRYIN + C[47:0] + E[47:0] + { (B[17:0] - D[17:0]) x A[17:0] }
0	0	1	0	CARRYIN + C[47:0] + E[47:0] - { (B[17:0] + D[17:0]) x A[17:0] }
0	0	1	1	CARRYIN + C[47:0] + E[47:0] - { (B[17:0] - D[17:0]) x A[17:0] }
0	1	0	0	CARRYIN + C[47:0] + E[47:0] + { (B[8:0] + D[8:0]) x A[17:9] + (B[17:9] + D[17:9]) x A[8:0] } x 29
0	1	0	1	CARRYIN + C[47:0] + E[47:0] + { (B[8:0] - D[8:0]) x A[17:9] + (B[17:9] - D[17:9]) x A[8:0] } x 29
0	1	1	0	CARRYIN + C[47:0] + E[47:0] + { (B[8:0] + D[8:0]) x A[17:9] - (B[17:9] + D[17:9]) x A[8:0] } x 29
0	1	1	1	CARRYIN + C[47:0] + E[47:0] + { (B[8:0] - D[8:0]) x A[17:9] - (B[17:9] - D[17:9]) x A[8:0] } x 29
1	0	0	0	P[17:0] = CARRYIN + { B[8:0] x A[8:0] } P[47:18] = C[47:18] + E[47:18] + { (B[17:9] + D[17:9]) x A[17:9] }
1	0	0	1	P[17:0] = CARRYIN + { B[8:0] x A[8:0] } P[47:18] = C[47:18] + E[47:18] + { (B[17:9] - D[17:9]) x A[17:9] }
1	0	1	0	P[17:0] = CARRYIN + { B[8:0] x A[8:0] } P[47:18] = C[47:18] + E[47:18] - { (B[17:9] + D[17:9]) x A[17:9] }
1	0	1	1	P[17:0] = CARRYIN + { B[8:0] x A[8:0] } P[47:18] = C[47:18] + E[47:18] - { (B[17:9] - D[17:9]) x A[17:9] }

Table 16-144. Truth Table—Computation of OVFL_CARRYOUT
OVFL_CARRYOUT_SEL	OVFL_CARRYOUT	Description
0	(SUM[49] ^ SUM[48]) \| (SUM[48] ^ SUM[47])	True if overflow or underflow occurred.
1	C[47] ^ E[47] ^ SUM[48]	A signal that can be used to extend the final adder in the fabric.

SUM[49:0] is defined similarly to P[47:0] as shown in Table 16-143, except that SUM is a 50-bit quantity so that no overflow can occur. SUM[48] is the carry out bit of a 48-bit final adder producing P[47:0].

Table 16-145. Truth Table for Control Registers ARSHFT17, CDIN_FDBK_SEL, PASUB, and SUB
AL_N	_AD_N	_BYPASS	CLK	_EN	_SL_N	_SD_N	D	Qn+1
0	AD_N	0	X	X	X	X	X	!AD_N
1	X	0	Not rising	X	X	X	X	Qn
1	X	0	?	0	X	X	X	Qn
1	X	0	?	1	0	SD_N	X	!SD_N
1	X	0	?	1	1	X	D	D
X	X	1	X	0	X	X	X	Qn
X	X	1	X	1	0	SD_N	X	!SD_N
X	X	1	X	1	1	X	D	D

Table 16-146. Truth Table—Data Registers A, B, P, and OVFL_CARRYOUT
AL_N	_BYPASS	CLK	_EN	_SRST_N	D	Qn+1
0	0	X	X	X	X	0
1	0	Not rising	X	X	X	Qn
1	0	?	0	X	X	Qn
1	0	?	1	0	X	0
1	0	?	1	1	D	D
X	1	X	0	X	X	Qn
X	1	X	1	0	X	0
X	1	X	1	1	D	D

Table 16-147. Truth Table—Data Registers C, CARRYIN, and D
_ARST_N	_BYPASS	CLK	_EN	_SRST_N	D	Qn+1
0	0	X	X	X	X	0
1	0	Not rising	X	X	X	Qn
1	0	?	0	X	X	Qn
1	0	?	1	0	X	0
1	0	?	1	1	D	D
X	1	X	0	X	X	Qn
X	1	X	1	0	X	0
X	1	X	1	1	D	D