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WIP on bignum2string

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This commit is contained in:
Justin Ethier 2022-06-05 20:58:24 -04:00
parent c68c60f007
commit 141e9ed7b5
2 changed files with 36 additions and 8 deletions
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10
include/cyclone/types.h
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@ -858,8 +858,8 @@ typedef struct {
// # define C_HALF_WORD_SIZE 32
// #else
// # define C_MOST_POSITIVE_FIXNUM 0x3fffffff
// # define C_WORD_SIZE 32
// # define C_HALF_WORD_SIZE 16
#define C_WORD_SIZE 32
#define C_HALF_WORD_SIZE 16
// #endif
//
// /* Tunable performance-related constants */
@ -884,13 +884,13 @@ typedef struct {
// #endif
//
// /* These might fit better in runtime.c? */
// #define C_fitsinbignumhalfdigitp(n) (C_BIGNUM_DIGIT_HI_HALF(n) == 0)
#define Cyc_fitsinbignumhalfdigitp(n) (C_BIGNUM_DIGIT_HI_HALF(n) == 0)
// #define C_BIGNUM_DIGIT_LENGTH C_WORD_SIZE
// #define C_BIGNUM_HALF_DIGIT_LENGTH C_HALF_WORD_SIZE
#define C_BIGNUM_HALF_DIGIT_LENGTH C_HALF_WORD_SIZE
// #define C_BIGNUM_BITS_TO_DIGITS(n) \
// (((n) + (C_BIGNUM_DIGIT_LENGTH - 1)) / C_BIGNUM_DIGIT_LENGTH)
// #define C_BIGNUM_DIGIT_LO_HALF(d) (C_uhword)(d)
// #define C_BIGNUM_DIGIT_HI_HALF(d) (C_uhword)((d) >> C_BIGNUM_HALF_DIGIT_LENGTH)
#define C_BIGNUM_DIGIT_HI_HALF(d) (uint16_t)((d) >> C_BIGNUM_HALF_DIGIT_LENGTH)
// #define C_BIGNUM_DIGIT_COMBINE(h,l) ((C_uword)(h) << C_BIGNUM_HALF_DIGIT_LENGTH|(C_uhword)(l))
//
// #define C_MOST_POSITIVE_32_BIT_FIXNUM 0x3fffffff

34
runtime.c
View file

@ -2449,10 +2449,10 @@ void bignum2string(void *data, object cont, bignum2_type *bn, int radix)
printf("radix power of two\n");
// TODO:
} else {
uint32_t base, *start, *scan, *end;
uint32_t base, *start, *scan, big_digit;
int steps, i;
// working copy??
// TODO: make a working copy of the bignum so we can perform destructive operations (??)
start = &(bn->sign);
start += 1;
@ -2461,11 +2461,39 @@ void bignum2string(void *data, object cont, bignum2_type *bn, int radix)
/* Calculate the largest power of radix that fits a halfdigit:
* steps = log10(2^halfdigit_bits), base = 10^steps
*/
for(steps = 0, base = radix; C_fitsinbignumhalfdigitp(base); base *= radix)
for(steps = 0, base = radix; Cyc_fitsinbignumhalfdigitp(base); base *= radix)
steps++;
base /= radix; /* Back down: we overshot in the loop */
while (scan > start) {
big_digit = bignum_digits_destructive_scale_down(start, scan, base);
if (*(scan-1) == 0) scan--; /* Adjust if we exhausted the highest digit */
for(i = 0; i < steps && index >= buf; ++i) {
C_word tmp = big_digit / radix;
*index-- = characters[big_digit - (tmp*radix)]; /* big_digit % radix */
big_digit = tmp;
}
}
assert(index >= buf-1);
free_tmp_bignum(working_copy);
/* Move index onto first nonzero digit. We're writing a bignum
here: it can't consist of only zeroes. */
while(*++index == '0');
if (negp) *--index = '-';
/* Shorten with distance between start and index. */
if (buf != index) {
i = C_header_size(string) - (index - buf);
C_memmove(buf, index, i); /* Move start of number to beginning. */
C_block_header(string) = C_STRING_TYPE | i; /* Mutate strlength. */
}
}
// TODO: call into cont with string
}
object Cyc_symbol2string(void *data, object cont, object sym)