ST10R272L-B0 View Datasheet(PDF) - STMicroelectronics
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ST10R272L-B0 Datasheet PDF : 4 Pages
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ST10R272L-B0 Errata Sheet
2.2 ST_MAC.9: COCMP INSTRUCTION INVERTED OPERANDS
According to the ST10 Family Programming Manual, the CoCmp instruction substracts a
40-bit signed operand from the 40-bit accumulator content (acc - op2\op1), and updates the
N, Z and C flags in the MSW register, leaving the accumulator unchanged.
In error, the reverse operation (op2\op1 - acc) has been implemented in the MacUnit. There-
fore, the N and C flags are set according to the reverse operation (Z flag is not affected).
Workaround: Change interpretation of the N and C flags in the MSW register.
2.3 ST_MAC.10: E-FLAG EVALUATION FOR COSHR AND COASHR INSTRUCTIONS
WHEN SATURATION MODE IS ENABLED
The Logical and the Arithmetic Right Shift instructions (CoShr/CoAshr) are specified not to be affected
by the saturation mode (MS bit of the MCW reg.). The result loaded in the accumulator is never saturat-
ed but the evaluation of E flag in the MSW register is erroneous when saturation mode is enabled
and the E flag would be set.
MS bit is set: saturation
mode is enabled
Example: Mov
R5,
#5555h
CoLoad R5, R5
Nop
Mov
MSW,
#007Fh
Nop
CoShr #1
Accumulator
SL E SV C Z N
-- ---- ----h - - - - - -
00 5555 5555h 0
00 5555 5555h 0
7F 5555 5555h 0
00
00
00
000
000
000
7F 5555 5555h 0 0 0 0 0 0
3F AAAA AAAAh 0 0 0 0 0 0
error
In this example, the E flag is kept clear however MAE is used.
Workaround: Disable saturation mode before using Logical and Arithmetic Right Shift in-
structions and re-enable it just after.
2/4
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