Output Buffer Length - 2025.2 English

The output buffer length is calculated using the formula shown in the OUT_BUFFER_LEN table: ceil((TP_F_LEN + TP_G_LEN - 1), LANES) for FULL mode, ceil(TP_F_LEN, LANES) for SAME mode, and ceil((TP_F_LEN - TP_G_LEN + 1), LANES) for VALID mode. Here, LANES is the number of parallel data lanes available in the AIE hardware, ensuring the buffer is always sized to the next multiple of the hardware lanes for efficient vector processing.

Formula for ceil:

ceil(a,b) ==> (((a+b-1)/b) * b)

Table 3 OUT_BUFFER_LEN

TP_COMPUTE_MODE	MODE NAME	OUT_BUFFER_LEN
0	FULL	ceil((TP_F_LEN + TP_G_LEN - 1), LANES)
1	SAME	ceil(TP_F_LEN, LANES)
2	VALID	ceil((TP_F_LEN - TP_G_LEN + 1), LANES)

Where:

• TP_F_LEN is the length of input F vector.
• TP_G_LEN is the length of input G vector.
• LANES is the number of parallel data lanes available in the AIE hardware, which depends on the data type combination used. See LANES

Table 4 LANES

InputF Data Type	InputG Data Type	Output Data Type	AIE-1 Lanes	AIE-ML Lanes	AIE-MLv2 Lanes
int8	int8	int16	0	32	64
int16	int16	int32	16	16	32
int32	int16	int32	8	16	32
cint16	int16	cint16	8	16	32
cint16	int16	cint32	8	16	32
cint16	int32	cint32	8	16	16
cint16	cint16	cint32	8	16	16
cint32	int16	cint32	4	16	16
cint32	cint16	cint32	4	8	16
float	float	float	8	32	16
cfloat	float	cfloat	4	0	0
cfloat	cfloat	cfloat	4	0	0
bfloat16	bfloat16	float	0	16	64

Example Config:

Data_F - int16,
Data_G - int16,
Data_Out - int32,
Func_Type = 1 (conv),
compute_mode = 0 (FULL), 1 (SAME), 2 (VALID),
F_LEN = 64,
G_LEN = 32.

in_F[F_LEN] = [1, 2, 3, ..., 64]
in_G[G_LEN] = [1, 2, 3, ..., 32]

FULL Mode:
   OUT_DATA_LEN = (TP_F_LEN + TP_G_LEN - 1) --> (64+32-1) --> 95
   LANES = 16 for int16xint16 data combo
   Output_Buffer_len = ceil(95,16) --> (((95+16-1)/16)*16) --> ((110/16)*16) --> (6*16)--> 96
   Therefore, the output buffer has 95 valid output samples and 1 zero sample.

SAME Mode:
   OUT_DATA_LEN = TP_F_LEN --> 64
   LANES = 16 for int16xint16 data combo
   Output_Buffer_len = ceil(64,16) --> (((64+16-1)/16)*16) --> ((79/16)*16) --> (4*16)--> 64
   Therefore, the output buffer has 64 valid output samples.

VALID Mode:
   OUT_DATA_LEN = (TP_F_LEN - TP_G_LEN + 1) --> (64-32+1) --> 33
   LANES = 16 for int16xint16 data combo
   Output_Buffer_len = ceil(33,16) --> (((33+16-1)/16)*16) --> ((48/16)*16) --> (3*16)--> 48
   Therefore, the output buffer has 33 valid output samples and 15 zero samples.