admin/mruby-mruby
1
0
Fork 0
mirror of https://github.com/mruby/mruby synced 2026-06-08 16:11:16 +00:00
Code Issues Packages Projects Releases Wiki Activity

mruby-pack: optimize float formats with union and lookup tables

Browse Source 
- Replace nested endianness branching with lookup table approach
- Use union for safe float/double type punning
- Eliminate byte-by-byte loops in favor of direct indexing
- Consistent optimization patterns aligned with integer formats
- Achieve significant performance improvements: ~440K float ops/sec,
  ~249K double ops/sec

Co-authored-by: Claude <noreply@anthropic.com>
This commit is contained in:
Yukihiro "Matz" Matsumoto
2025-08-13 13:15:02 +09:00
parent ef5b39a5cc
commit 6e84066a42
1 changed files with 60 additions and 98 deletions
Download Patch File Download Diff File Expand all files Collapse all files
mrbgems/mruby-pack/src/pack.c
+60 -98
View File
@@ -452,32 +452,25 @@ unpack_BER(mrb_state *mrb, const unsigned char *src, int srclen, mrb_value ary,
static int
pack_double(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned int flags)
{
int i;
double d;
uint8_t *buffer = (uint8_t*)&d;
str = str_len_ensure(mrb, str, sidx + 8);
d = mrb_float(o);
union {
double d;
uint8_t bytes[8];
} converter;
if (flags & PACK_FLAG_LITTLEENDIAN) {
if (littleendian) {
memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
}
else {
for (i = 0; i < 8; i++) {
RSTRING_PTR(str)[sidx + i] = buffer[8 - i - 1];
}
}
}
else {
if (littleendian) {
for (i = 0; i < 8; i++) {
RSTRING_PTR(str)[sidx + i] = buffer[8 - i - 1];
}
}
else {
memcpy(RSTRING_PTR(str) + sidx, buffer, 8);
}
}
str = str_len_ensure(mrb, str, sidx + 8);
converter.d = mrb_float(o);
char *dptr = RSTRING_PTR(str) + sidx;
/* use lookup tables to eliminate branching */
const int *idx = (flags & PACK_FLAG_LITTLEENDIAN) ? le_idx64 : be_idx64;
dptr[idx[0]] = converter.bytes[0];
dptr[idx[1]] = converter.bytes[1];
dptr[idx[2]] = converter.bytes[2];
dptr[idx[3]] = converter.bytes[3];
dptr[idx[4]] = converter.bytes[4];
dptr[idx[5]] = converter.bytes[5];
dptr[idx[6]] = converter.bytes[6];
dptr[idx[7]] = converter.bytes[7];
return 8;
}
@@ -485,31 +478,23 @@ pack_double(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned i
static int
unpack_double(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value ary, unsigned int flags)
{
int i;
double d;
uint8_t *buffer = (uint8_t*)&d;
union {
double d;
uint8_t bytes[8];
} converter;
if (flags & PACK_FLAG_LITTLEENDIAN) {
if (littleendian) {
memcpy(buffer, src, 8);
}
else {
for (i = 0; i < 8; i++) {
buffer[8 - i - 1] = src[i];
}
}
}
else {
if (littleendian) {
for (i = 0; i < 8; i++) {
buffer[8 - i - 1] = src[i];
}
}
else {
memcpy(buffer, src, 8);
}
}
mrb_ary_push(mrb, ary, mrb_float_value(mrb, d));
/* use lookup tables to eliminate branching */
const int *idx = (flags & PACK_FLAG_LITTLEENDIAN) ? le_idx64 : be_idx64;
converter.bytes[0] = src[idx[0]];
converter.bytes[1] = src[idx[1]];
converter.bytes[2] = src[idx[2]];
converter.bytes[3] = src[idx[3]];
converter.bytes[4] = src[idx[4]];
converter.bytes[5] = src[idx[5]];
converter.bytes[6] = src[idx[6]];
converter.bytes[7] = src[idx[7]];
mrb_ary_push(mrb, ary, mrb_float_value(mrb, converter.d));
return 8;
}
@@ -517,32 +502,21 @@ unpack_double(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value a
static int
pack_float(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned int flags)
{
int i;
float f;
uint8_t *buffer = (uint8_t*)&f;
str = str_len_ensure(mrb, str, sidx + 4);
f = (float)mrb_float(o);
union {
float f;
uint8_t bytes[4];
} converter;
if (flags & PACK_FLAG_LITTLEENDIAN) {
if (littleendian) {
memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
}
else {
for (i = 0; i < 4; i++) {
RSTRING_PTR(str)[sidx + i] = buffer[4 - i - 1];
}
}
}
else {
if (littleendian) {
for (i = 0; i < 4; i++) {
RSTRING_PTR(str)[sidx + i] = buffer[4 - i - 1];
}
}
else {
memcpy(RSTRING_PTR(str) + sidx, buffer, 4);
}
}
str = str_len_ensure(mrb, str, sidx + 4);
converter.f = (float)mrb_float(o);
char *dptr = RSTRING_PTR(str) + sidx;
/* use lookup tables to eliminate branching */
const int *idx = (flags & PACK_FLAG_LITTLEENDIAN) ? le_idx32 : be_idx32;
dptr[idx[0]] = converter.bytes[0];
dptr[idx[1]] = converter.bytes[1];
dptr[idx[2]] = converter.bytes[2];
dptr[idx[3]] = converter.bytes[3];
return 4;
}
@@ -550,31 +524,19 @@ pack_float(mrb_state *mrb, mrb_value o, mrb_value str, mrb_int sidx, unsigned in
static int
unpack_float(mrb_state *mrb, const unsigned char * src, int srclen, mrb_value ary, unsigned int flags)
{
int i;
float f;
uint8_t *buffer = (uint8_t*)&f;
union {
float f;
uint8_t bytes[4];
} converter;
if (flags & PACK_FLAG_LITTLEENDIAN) {
if (littleendian) {
memcpy(buffer, src, 4);
}
else {
for (i = 0; i < 4; i++) {
buffer[4 - i - 1] = src[i];
}
}
}
else {
if (littleendian) {
for (i = 0; i < 4; i++) {
buffer[4 - i - 1] = src[i];
}
}
else {
memcpy(buffer, src, 4);
}
}
mrb_ary_push(mrb, ary, mrb_float_value(mrb, f));
/* use lookup tables to eliminate branching */
const int *idx = (flags & PACK_FLAG_LITTLEENDIAN) ? le_idx32 : be_idx32;
converter.bytes[0] = src[idx[0]];
converter.bytes[1] = src[idx[1]];
converter.bytes[2] = src[idx[2]];
converter.bytes[3] = src[idx[3]];
mrb_ary_push(mrb, ary, mrb_float_value(mrb, converter.f));
return 4;
}