ST20-C1 STMICROELECTRONICS [STMicroelectronics], ST20-C1 Datasheet - Page 62

• Manufacturer Part Number: ST20-C1
• Description: Instruction Set Reference Manual
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

5.6 Scaling
Under shifting (by less than 8) is used for magnitude reduction (most suitable for
smacloop ) by 4 bits (x16) using mac_scale=1 or 8 bits (x256) using mac_scale=0.
Under-shifting by 4 bits is shown in Figure 5.5, and by 8 bits in Figure 5.6.
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15
15
47
47
X data value
X data value
Figure 5.5 Coefficient scaling with mac_mode set to 1
Figure 5.6 Coefficient scaling with mac_mode set to 0
35
Add to internal accumulator
Add to internal accumulator
0
0
31
23
23
15
4
Y data value
15
0
0
<< 4
Y data value
0
4
0
0
0