Routines |
Prev: 2D8C | Up: Map | Next: 2DA2 |
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.
|
||||||||||||
INT_STORE | 2D8E | PUSH HL | The pointer to the first location is saved. | |||||||||
2D8F | LD (HL),$00 | The first byte is set to zero. | ||||||||||
2D91 | INC HL | Point to the second location. | ||||||||||
2D92 | 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.
|
||||||||||||
2D93 | INC HL | Point to the third location. | ||||||||||
2D94 | LD A,E | Collect the less significant byte. | ||||||||||
2D95 | XOR C | Two's complement it if the number is negative. | ||||||||||
2D96 | SUB C | |||||||||||
2D97 | LD (HL),A | Store the byte. | ||||||||||
2D98 | INC HL | Point to the fourth location. | ||||||||||
2D99 | LD A,D | Collect the more significant byte. | ||||||||||
2D9A | ADC A,C | Two's complement it if the number is negative. | ||||||||||
2D9B | XOR C | |||||||||||
2D9C | LD (HL),A | Store the byte. | ||||||||||
2D9D | INC HL | Point to the fifth location. | ||||||||||
2D9E | LD (HL),$00 | The fifth byte is set to zero. | ||||||||||
2DA0 | POP HL | Return with HL pointing to the first byte of n on the stack. | ||||||||||
2DA1 | RET |
Prev: 2D8C | Up: Map | Next: 2DA2 |