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bugfix for log()/pow: minimize stack usage

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This commit is contained in:
Jeff Wang 2019-10-06 21:04:23 -04:00
parent 75dd499630
commit 5f0cec0bad
2 changed files with 34 additions and 31 deletions
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61
src/decn/decn.c
View File

@ -51,7 +51,8 @@ static const uint8_t num_digits_display = DEC80_NUM_LSU*2;
static const uint8_t num_digits_display = 16;
#endif
__idata dec80 AccDecn, BDecn;
dec80 AccDecn;
__idata dec80 BDecn;
__idata dec80 TmpDecn; //used by add_decn() and mult_decn()
__idata dec80 Tmp2Decn; //used by recip_decn() and ln_decn()
__idata dec80 Tmp3Decn; //used by recip_decn() and ln_decn()
@ -111,25 +112,26 @@ static void zero_remaining_dec80(dec80* dest, uint8_t digit100){
}
}
static uint8_t shift_high = 0, shift_low = 0, shift_old = 0;
static uint8_t shift_i;
static void shift_right(dec80* x){
uint8_t high = 0, low = 0, old_low = 0;
uint8_t i;
for (i = 0; i < DEC80_NUM_LSU; i++){
high = x->lsu[i] / 10;
low = x->lsu[i] % 10;
x->lsu[i] = high + (old_low*10);
old_low = low;
shift_high = shift_low = shift_old = 0;
for (shift_i = 0; shift_i < DEC80_NUM_LSU; shift_i++){
shift_high = x->lsu[shift_i] / 10;
shift_low = x->lsu[shift_i] % 10;
x->lsu[shift_i] = shift_high + ( shift_old*10);
shift_old = shift_low;
}
}
static void shift_left(dec80* x){
uint8_t high = 0, low = 0, old_high = 0;
int8_t i;
for (i = DEC80_NUM_LSU - 1; i >= 0 ; i--){
high = x->lsu[i] / 10;
low = x->lsu[i] % 10;
x->lsu[i] = old_high + (low*10);
old_high = high;
shift_high = shift_low = shift_old = 0;
for (shift_i = DEC80_NUM_LSU - 1; shift_i < 255; shift_i--){
shift_high = x->lsu[shift_i] / 10;
shift_low = x->lsu[shift_i] % 10;
x->lsu[shift_i] = shift_old + ( shift_low*10);
shift_old = shift_high;
}
}
@ -877,7 +879,6 @@ static const dec80 LN_A_ARR[NUM_A_ARR] = {
void ln_decn(void){
uint8_t j, k;
exp_t initial_exp;
#define B_j Tmp2Decn
#define NUM_TIMES Tmp3Decn
@ -889,7 +890,7 @@ void ln_decn(void){
//normalize
remove_leading_zeros(&AccDecn);
//scale to between 1 and 10
initial_exp = get_exponent(&AccDecn) + 1;
NUM_TIMES.exponent = get_exponent(&AccDecn) + 1; //store initial exp in NUM_TIMES.exponent
AccDecn.exponent = 0;
#ifdef DEBUG_LOG
decn_to_str_complete(&AccDecn);
@ -903,7 +904,7 @@ void ln_decn(void){
copy_decn(&B_j, &AccDecn); //b_j = accum = 10 - A
#ifdef DEBUG_LOG
decn_to_str_complete(&AccDecn);
printf("ln() initial accum: %s (%d)\n", Buf, initial_exp);
printf("ln() initial accum: %s (%d)\n", Buf, NUM_TIMES.exponent);
#endif
//track number of times multiplied by a_arr[j]
@ -980,32 +981,32 @@ void ln_decn(void){
//accum = -accum;
negate_decn(&AccDecn);
//add back in initial exponent
//add back in initial exponent (stored in NUM_TIMES.exponent)
copy_decn(&B_j, &AccDecn); //temporarily store accum in B_j
set_dec80_zero(&AccDecn);
//check if negative
if (initial_exp < 0){
if (NUM_TIMES.exponent < 0){
j = 1; //track is_neg
initial_exp = -initial_exp;
NUM_TIMES.exponent = -NUM_TIMES.exponent;
} else {
j = 0;
}
//check if too big for single lsu
#ifdef EXP16
if (initial_exp >= 10000){
AccDecn.lsu[0] = initial_exp / 10000;
initial_exp = initial_exp % 10000;
AccDecn.lsu[1] = initial_exp / 100;
AccDecn.lsu[2] = initial_exp % 100;
if (NUM_TIMES.exponent >= 10000){
AccDecn.lsu[0] = NUM_TIMES.exponent / 10000;
NUM_TIMES.exponent = NUM_TIMES.exponent % 10000;
AccDecn.lsu[1] = NUM_TIMES.exponent / 100;
AccDecn.lsu[2] = NUM_TIMES.exponent % 100;
AccDecn.exponent = 4;
} else
#endif
if (initial_exp >= 100){
AccDecn.lsu[0] = initial_exp / 100;
AccDecn.lsu[1] = initial_exp % 100;
if (NUM_TIMES.exponent >= 100){
AccDecn.lsu[0] = NUM_TIMES.exponent / 100;
AccDecn.lsu[1] = NUM_TIMES.exponent % 100;
AccDecn.exponent = 2;
} else {
AccDecn.lsu[0] = initial_exp;
AccDecn.lsu[0] = NUM_TIMES.exponent;
AccDecn.exponent = 1;
}
//check if need to negate

4
src/decn/decn.h
View File

@ -55,7 +55,9 @@ static const dec80 DECN_LN_10 = {
exp_t get_exponent(const dec80* x);
void copy_decn(dec80* dest, const dec80* src);
extern __idata dec80 AccDecn, BDecn, Tmp4Decn;
extern dec80 AccDecn;
extern __idata dec80 BDecn, Tmp4Decn;
void build_dec80(__xdata const char* signif_str, exp_t exponent);