mirror of
https://github.com/RevCurtisP/C02.git
synced 2024-11-22 16:34:15 +00:00
101 lines
4.1 KiB
Plaintext
101 lines
4.1 KiB
Plaintext
|
Standard Library Functions for C02 Programs
|
||
|
|
|
||
|
|
At the beginning of the program use the directives
|
||
|
|
|
||
|
|
#include <stdlib.h02>
|
||
|
|
|
||
|
|
The following functions are defined:
|
||
|
|
|
||
|
|
c = abs(b); Returns the absolute value of the two's-complement
|
||
|
|
byte b.
|
||
|
|
|
||
|
|
In two's-complement arithmetic, the unsigned values
|
||
|
|
0 - 127 are considered positive, while the unsigned
|
||
|
|
values 128 - 255 are considered negative.
|
||
|
|
|
||
|
|
c = atoc(&s); Returns the numeric value of the string in array s.
|
||
|
|
|
||
|
|
Does not skip leading white-space characters and
|
||
|
|
stops when first non-digit character is encountered.
|
||
|
|
|
||
|
|
Overflows are ignored, so numbers greater than 255
|
||
|
|
will be returned modulo 256.
|
||
|
|
|
||
|
|
ctoa(c, &s); Stores the ASCII representation of usigned byte c
|
||
|
|
as a null-terminated string in array s.
|
||
|
|
|
||
|
|
The array must be dimensioned to at least 4 bytes.
|
||
|
|
|
||
|
|
c = max(b, d); Returns the greater of the two unsigned bytes b and d.
|
||
|
|
|
||
|
|
c = min(b, d); Returns the lesser of the two unsigned bytes b and d.
|
||
|
|
|
||
|
|
c = mult(d, r); Returns the product of byte d times byte r.
|
||
|
|
|
||
|
|
Overflows are ignored, so results greater than 255
|
||
|
|
will be returned modulo 256.
|
||
|
|
|
||
|
|
c = div(n, d); Returns the quotient of byte n divided by byte d.
|
||
|
|
|
||
|
|
Remainders are discarded and division by 0 returns ??.
|
||
|
|
|
||
|
|
c = rand(); Returns pseudo-random number. Sequence repeats
|
||
|
|
after 255 repeated calls. The generator must be
|
||
|
|
seeded using the rands() function before the first
|
||
|
|
call to rand().
|
||
|
|
|
||
|
|
rands(n); Seeds the pseudo-random number generator.
|
||
|
|
|
||
|
|
If n is 0, the generator is seeded with a system
|
||
|
|
seed value. This should be used for normal operation.
|
||
|
|
|
||
|
|
If n is not 0. then it is used as the seed. This can
|
||
|
|
be used for program testing or when a predictable
|
||
|
|
pattern is needed.
|
||
|
|
|
||
|
|
Note: The system seed is generated by a counter or
|
||
|
|
timer. On systems that don't use a timer, the counter
|
||
|
|
is cycled by the keyboard routines, so the getkey()
|
||
|
|
or getchr() function must called at least once before
|
||
|
|
a rands(0) call.
|
||
|
|
|
||
|
|
c = shiftl(b, n); Returns byte b shifted n bits to the left, filling
|
||
|
|
with 0's from the right.
|
||
|
|
|
||
|
|
If n is greater than 8, all bits will be shifted out,
|
||
|
|
and a value of 0 is treated as 256.
|
||
|
|
|
||
|
|
c = shiftr(b, n); Returns byte b shifted n bits to the right, filling
|
||
|
|
with 0's from the left.
|
||
|
|
|
||
|
|
If n is greater than 8, all bits will be shifted out,
|
||
|
|
and a value of 0 is treated as 256.
|
||
|
|
|
||
|
|
Note: Using the shiftl() or shiftr() functions with
|
||
|
|
an asignment generates 9 to 12 bytes of code, whereas
|
||
|
|
the << and >> post-operators generate either 2 or 3
|
||
|
|
bytes each. So for a constant number of shifts, the
|
||
|
|
post-operators will generate smaller code for less
|
||
|
|
than 5 shifts and will always be faster.
|
||
|
|
|
||
|
|
|
||
|
|
Note: This library expects the following function to be defined
|
||
|
|
|
||
|
|
setsrc(&s); Set source string pointer and initialize index
|
||
|
|
|
||
|
|
along with the zero page variables
|
||
|
|
|
||
|
|
srclo,srchi: Source string pointer
|
||
|
|
|
||
|
|
as well as the transient variables
|
||
|
|
|
||
|
|
temp0 Temporary storage
|
||
|
|
temp1
|
||
|
|
temp2
|
||
|
|
|
||
|
|
and the static variables
|
||
|
|
|
||
|
|
random Psuedo-random number generator seed Value
|
||
|
|
rdseed System generated initial seed (counter or timer)
|
||
|
|
|