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Routines |
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This subroutine stores a small integer n (-65535<=n<=65535) in the location addressed by HL and the four following locations, i.e. n replaces the first (or second) number at the top of the calculator stack. The subroutine returns HL pointing to the first byte of n on the stack.
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INT_STORE | 11662 | PUSH HL | The pointer to the first location is saved. | ||||||||||
11663 | LD (HL),0 | The first byte is set to zero. | |||||||||||
11665 | INC HL | Point to the second location. | |||||||||||
11666 | LD (HL),C | Enter the second byte. | |||||||||||
The same mechanism is now used as in INT_FETCH to two's complement negative numbers. This is needed e.g. before and after the multiplication of small integers. Addition is however performed without any further two's complementing before or afterwards.
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11667 | INC HL | Point to the third location. | |||||||||||
11668 | LD A,E | Collect the less significant byte. | |||||||||||
11669 | XOR C | Two's complement it if the number is negative. | |||||||||||
11670 | SUB C | ||||||||||||
11671 | LD (HL),A | Store the byte. | |||||||||||
11672 | INC HL | Point to the fourth location. | |||||||||||
11673 | LD A,D | Collect the more significant byte. | |||||||||||
11674 | ADC A,C | Two's complement it if the number is negative. | |||||||||||
11675 | XOR C | ||||||||||||
11676 | LD (HL),A | Store the byte. | |||||||||||
11677 | INC HL | Point to the fifth location. | |||||||||||
11678 | LD (HL),0 | The fifth byte is set to zero. | |||||||||||
11680 | POP HL | Return with HL pointing to the first byte of n on the stack. | |||||||||||
11681 | RET |
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