Page 196 - Introduction to Microcontrollers Architecture, Programming, and Interfacing of The Motorola 68HC12

PROBLEMS 173

PROBLEMS

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1. Write a program segment that evaluates the quadratic function ax + bx + c, where
signed 16-bit arguments a, b, c, and x are stored on the stack and are initialized to 1, 2,
3, and 4, respectively, by pushing 4, then 3, then 2, and then 1, in the manner of Figure
6.6, and the output is stored on the stack in a "hole" created by a LEAS ~2, SP
instruction before the segment begins. In order to demonstrate local variables, as part of
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your program segment, save 16-bit value ax in a 16-bit local variable on the stack,
2 . Write a shortest program segment that computes the parallel resistance of two
resistors Rl and R2, where unsigned 16-bit arguments Rl and R2 are stored in local
variables, which are both initialized to 100, by pushing 100 and then 100, and the result
is stored on the stack in a "hole" created by a LEAS -2, SP instruction, in the manner
of Figure 6.6. In order to demonstrate local variables, as part of your program segment,
store Rl times R2 in a 32-bit local variable on the stack.

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3 . Write a program segment that evaluates the quadratic function ax + bx + c, where
signed 16-bit arguments a, b, c, and x are stored in local variables PARA, PARE, PARC,
and PARK on the stack, which are initialized to 1, 2, 3, and 4, respectively, and the
output is returned in local variable RESULT on the stack, in the manner of Figure 6.JO.
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In order to demonstrate local variables, as part of your program segment, store ax in a
16-bit local variable on the stack.
4 , Write a shortest program segment that computes the parallel resistance of two
resistors Rl and R2, where unsigned 16-bit arguments are stored in local variables named
Rl and R2, which are both initialized to 100 and the output is returned in register D, in
the manner of Figure 6.10. In order to demonstrate local variables, as part of your
program segment, store Rl times R2 in a 32-bit local variable on the stack.
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5 . Write a program segment that evaluates the quadratic function ax + bx + c, where
signed 16-bit arguments a, b, c, and x are stored in local variables PARA, PARE, PARC,
and PARX on the stack as outer segment local variables, which are initialized to 1, 2, 3,
and 4, respectively, and the output is returned in register D, in the manner of Figure
6.13. In order to demonstrate local variables, as part of your inner program segment,
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store ax in a 16-bit local variable on the stack.
6 . Write a shortest program segment that computes the parallel resistance of two
resistors Rl and R2, where unsigned 16-bit arguments are stored in outer segment local
variables Rl and R2, which are both intitilaized to 100, and the output is returned in
register D, in the manner of Figure 6.13. To demonstrate local variables, as part of your
inner program segment, store Rl times R2 in a 32-bit local variable on the stack.

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7 . Write a program segment that evaluates the quadratic function ax + bx + c, where
signed 16-bit arguments a, b, c, and x are stored in local variables PARA, PARE, PARC,
and PARX on the stack as outer segment local variables, which are initialized to 1, 2, 3,
and 4, respectively, and the output is returned in register D, using a stack marker in the
manner of Figure 6.14. In order to demonstrate local variables, as part of your inner
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program segment, store ax in a 16-bit local variable on the stack.