ST ST10F276E - The Multiply; Divide High Register MDH; The Multiply; Divide Low Register MDL

The central processing unit (CPU) UM0404
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This control mechanism is not triggered, and no stack trap is generated, when:
• The stack pointer SP is directly updated via MOV instructions.
• The limits of the stack area (STKOV, STKUN) are changed, so that SP is outside of the
new limits.
3.4.13 The multiply / divide high register MDH
This register is a part of the 32-bit multiply/divide register, which is implicitly used by the
CPU, when it performs a multiplication or a division. After a multiplication, this non-bit-
addressable register represents the high order 16 bits of the 32-bit result. For long divisions,
the MDH register must be loaded with the high order 16 bits of the 32-bit dividend before the
division is started. After any division, register MDH represents the 16-bit remainder.
MDH (FE0Ch / 06h) SFR Reset Value: 0000h
Whenever this register is updated via software, the Multiply/Divide Register In Use (MDRIU)
flag in the Multiply/Divide Control register (MDC) is set to '1'. When a multiplication or
division is interrupted before its completion and when a new multiply or divide operation is to
be performed within the interrupt service routine, register MDH must be saved along with
registers MDL and MDC to avoid erroneous results.
A detailed description of how to use the MDH register for programming multiply and divide
algorithms can be found in Section 27: System programming on page 545.
3.4.14 The multiply / divide low register MDL
This register is a part of the 32-bit multiply/divide register, which is implicitly used by the
CPU, when it performs a multiplication or a division. After a multiplication, this non-bit-
addressable register represents the low order 16 bits of the 32-bit result. For long divisions,
the MDL register must be loaded with the low order 16 bits of the 32-bit dividend before the
division is started. After any division, register MDL represents the 16-bit quotient.
MDL (FE0Eh / 07h) SFR Reset Value: 0000h
1514131211109876543210
mdh
RW
Bit Function
MDH Specifies the high order 16 bits of the 32-bit multiply and divide register MD.
1514131211109876543210
mdl
RW
Bit Function
mdl Specifies the low order 16 bits of the 32-bit multiply and divide register MD.