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86 lines
2.6 KiB
C
86 lines
2.6 KiB
C
#include <fenv.h>
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#include <string.h>
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#include <locale.h>
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#include <pthread.h>
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#include "notcurses/notcurses.h"
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const char *ncmetric(uintmax_t val, uintmax_t decimal, char *buf, int omitdec,
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unsigned mult, int uprefix){
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// these two must have the same number of elements
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const wchar_t prefixes[] = L"KMGTPEZY"; // 10^21-1 encompasses 2^64-1
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const wchar_t subprefixes[] = L"mµnpfazy"; // 10^24-1
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unsigned consumed = 0;
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uintmax_t dv;
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fesetround(FE_TOWARDZERO);
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if(decimal == 0 || mult == 0){
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return NULL;
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}
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if(decimal > UINTMAX_MAX / 10){
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return NULL;
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}
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dv = mult;
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if(decimal <= val || val == 0){
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// FIXME verify that input < 2^89, wish we had static_assert() :/
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while((val / decimal) >= dv && consumed < sizeof(prefixes) / sizeof(*prefixes)){
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dv *= mult;
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++consumed;
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if(UINTMAX_MAX / dv < mult){ // near overflow--can't scale dv again
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break;
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}
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}
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}else{
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while(val < decimal && consumed < sizeof(subprefixes) / sizeof(*subprefixes)){
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val *= mult;
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++consumed;
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if(UINTMAX_MAX / dv < mult){ // near overflow--can't scale dv again
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break;
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}
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}
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}
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int sprintfed;
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if(dv != mult){ // if consumed == 0, dv must equal mult
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if(val / dv > 0){
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++consumed;
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}else{
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dv /= mult;
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}
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val /= decimal;
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// Remainder is val % dv, but we want a percentage as scaled integer.
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// Ideally we would multiply by 100 and divide the result by dv, for
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// maximum accuracy (dv might not be a multiple of 10--it is not for
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// 1,024). That can overflow with large 64-bit values, but we can first
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// divide both sides by mult, and then scale by 100.
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if(omitdec && (val % dv) == 0){
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sprintfed = sprintf(buf, "%ju%lc", val / dv, prefixes[consumed - 1]);
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}else{
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sprintfed = sprintf(buf, "%.2f%lc", (double)val / dv, prefixes[consumed - 1]);
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}
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if(uprefix){
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buf[sprintfed] = uprefix;
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buf[sprintfed + 1] = '\0';
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}
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return buf;
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}
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// unscaled output, consumed == 0, dv == mult
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// val / decimal < dv (or we ran out of prefixes)
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if(omitdec && val % decimal == 0){
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if(consumed){
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sprintfed = sprintf(buf, "%ju%lc", val / decimal, subprefixes[consumed - 1]);
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}else{
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sprintf(buf, "%ju", val / decimal);
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}
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}else{
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if(consumed){
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sprintfed = sprintf(buf, "%.2f%lc", (double)val / decimal, subprefixes[consumed - 1]);
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}else{
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sprintf(buf, "%.2f", (double)val / decimal);
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}
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}
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if(consumed && uprefix){
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buf[sprintfed] = uprefix;
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buf[sprintfed + 1] = '\0';
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}
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return buf;
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}
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