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Change to use LUT for glyph->number in VM 

Faster than the bit twiddling, given the types of data and programs we
have now. Also means we can drop the distinction between 'safe' and
'unsafe' indexing when bounds checking is or is not required. Also now
gives consistent results with orca JS for 'strange' symbols like :, ;,
etc.
master
cancel 5 years ago
parent
df82ab8d23
commit
41a5089d96
1 changed files with 19 additions and 45 deletions
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  1. 64
      sim.c

64
sim.c
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@ -4,48 +4,24 @@
//////// Utilities
static Glyph const indexed_glyphs[] = {
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', // 0 - 11
'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 12 - 23
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', // 24 - 35
'0', '1', '2', '3', '4', '5', '6', '7', '8', '9', 'a', 'b', // 0-11
'c', 'd', 'e', 'f', 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n', // 12-23
'o', 'p', 'q', 'r', 's', 't', 'u', 'v', 'w', 'x', 'y', 'z', // 24-35
};
enum { Glyphs_index_count = sizeof indexed_glyphs };
// Always returns 0 through (sizeof indexed_glyphs) - 1, and works on
// capitalized glyphs as well. The index of the lower-cased glyph is returned
// if the glyph is capitalized.
#if 1
// Branchless implementation. Assumes two's complement.
static Usz index_of(Glyph c) {
int i = c;
enum {
// All number chars have this bit set. Some alpha chars do.
Num_bit = 1 << 4,
// All alpha chars have this bit set. No number chars do.
Alpha_bit = 1 << 6,
// The bits we use from a number char (0000 1111) to get an index number
Lower_4 = 0xF,
// The bits we use from an alpha char (0001 1111) to get an index number
Lower_5 = 0x1F,
};
union {
uint32_t u;
int32_t i;
} pui;
// Turn the alpha bit into a mask of all 32 bits
pui.u = (uint32_t)(i & Alpha_bit) << UINT32_C(25);
int alpha_mask = pui.i >> 31;
// Turn the number bit into a mask of all 32 bits
pui.u = (uint32_t)(i & Num_bit) << UINT32_C(27);
int num_mask = pui.i >> 31;
// If it's an alpha char, we add 9 to it, bringing 'a'/'A' from 1 to 10, 'b'
// to 11, etc.
return (Usz)((i & ((alpha_mask & Lower_5) | (num_mask & Lower_4))) +
(9 & alpha_mask));
// If the glyph might be a non-valid char in certain ranges (like '^' char)
// we will return a number here greater than 35. We could do % 36 here if we
// wanted to be really safe.
}
static U8 index_lut[128] = {
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 0-15
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 16-31
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, // 32-47
0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 0, 0, 0, 0, 0, 0, // 48-63
0, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 64-79
25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 0, 0, 0, 0, 0, // 80-95
0, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, // 96-111
25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 0, 0, 0, 0, 0}; // 112-127
static ORCA_FORCEINLINE Usz index_of(Glyph c) { return index_lut[c & 0x7f]; }
#else
// Reference implementation
static Usz index_of(Glyph c) {
@ -61,8 +37,6 @@ static Usz index_of(Glyph c) {
}
#endif
static Usz safe_index_of(Glyph c) { return index_of(c) % 36; }
static inline Glyph glyph_of(Usz index) {
assert(index < Glyphs_index_count);
return indexed_glyphs[index];
@ -281,7 +255,7 @@ BEGIN_OPERATOR(midicc)
oe->oevent_type = Oevent_type_midi_cc;
oe->channel = (U8)channel;
oe->control = (U8)index_of(control_g);
oe->value = (U8)(safe_index_of(value_g) * 127 / 35); // 0~35 -> 0~127
oe->value = (U8)(index_of(value_g) * 127 / 35); // 0~35 -> 0~127
END_OPERATOR
BEGIN_OPERATOR(comment)
@ -422,8 +396,8 @@ BEGIN_OPERATOR(midipb)
(Oevent_midi_pb *)oevent_list_alloc_item(extra_params->oevent_list);
oe->oevent_type = Oevent_type_midi_pb;
oe->channel = (U8)channel;
oe->msb = (U8)(safe_index_of(msb_g) * 127 / 35); // 0~35 -> 0~127
oe->lsb = (U8)(safe_index_of(lsb_g) * 127 / 35);
oe->msb = (U8)(index_of(msb_g) * 127 / 35); // 0~35 -> 0~127
oe->lsb = (U8)(index_of(lsb_g) * 127 / 35);
END_OPERATOR
BEGIN_OPERATOR(add)
@ -548,7 +522,7 @@ BEGIN_OPERATOR(konkat)
PORT(0, i + 1, IN);
Glyph var = PEEK(0, i + 1);
if (var != '.') {
Usz var_idx = safe_index_of(var);
Usz var_idx = index_of(var);
if (var_idx != 0) {
Glyph result = extra_params->vars_slots[var_idx];
PORT(1, i + 1, OUT);
@ -710,12 +684,12 @@ BEGIN_OPERATOR(variable)
Glyph right = PEEK(0, 1);
if (left != '.') {
// Write
Usz var_idx = safe_index_of(left);
Usz var_idx = index_of(left);
extra_params->vars_slots[var_idx] = right;
} else if (right != '.') {
// Read
PORT(1, 0, OUT);
Usz var_idx = safe_index_of(right);
Usz var_idx = index_of(right);
Glyph result = extra_params->vars_slots[var_idx];
POKE(1, 0, result);
}

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