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update upkr (new tweaked compressed format)

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This commit is contained in:
Dennis Ranke
2021-12-27 17:31:08 +01:00
parent 0f795ae061
commit 462dc3a1c6
7 changed files with 20 additions and 15 deletions
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27
platform/src/loader.cwa
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@@ -88,14 +88,17 @@ export fn uncompress(src_ptr: i32, dest_ptr: i32) -> i32 {
let i: i32;
loop init_contexts {
i!0x3c000 = 0x800;
branch_if (i := i + 4) < (256 + 1 + 128) * 4: init_contexts
i?0x3c000 = 0x80;
branch_if (i := i + 1) < 256 + 1 + 128: init_contexts
}
let prev_was_match: i32;
block finished {
loop unpack_loop {
if upkr_bit(0) {
if upkr_bit(256) {
let inline new_offset = if prev_was_match { 1 } else { upkr_bit(256) };
if new_offset {
offset = upkr_length(257) - 1;
branch_if !offset: finished
}
@@ -105,6 +108,7 @@ export fn uncompress(src_ptr: i32, dest_ptr: i32) -> i32 {
dest_ptr = dest_ptr + 1;
branch_if (length := length - 1): copy;
}
prev_was_match = 1;
} else {
// literal
i = 0;
@@ -115,6 +119,7 @@ export fn uncompress(src_ptr: i32, dest_ptr: i32) -> i32 {
}
dest_ptr?0 = byte;
dest_ptr = dest_ptr + 1;
prev_was_match = 0;
}
branch unpack_loop;
}
@@ -138,28 +143,28 @@ fn upkr_length(context_index: i32) -> i32 {
}
fn upkr_bit(context_index: i32) -> i32 {
let prob = (context_index * 4)!0x3c000;
let prob = context_index?0x3c000;
loop refill {
if upkr_state < 1<<16 {
if upkr_state < 1<<12 {
upkr_state = (upkr_state << 8) | upkr_src_ptr?0;
upkr_src_ptr = upkr_src_ptr + 1;
branch refill;
}
}
let lazy state_low = upkr_state & 0xfff;
let lazy state_low = upkr_state & 0xff;
let bit = state_low < prob;
if bit {
upkr_state = prob * (upkr_state >> 12) + state_low;
prob = prob + ((0x1000 - prob) >> 4);
upkr_state = prob * (upkr_state >> 8) + state_low;
prob = prob + ((0x108 - prob) >> 4);
} else {
upkr_state = (0x1000 - prob) * (upkr_state >> 12) + state_low - prob;
prob = prob - (prob >> 4);
upkr_state = (0x100 - prob) * (upkr_state >> 8) + state_low - prob;
prob = prob - ((prob + 8) >> 4);
}
(context_index * 4)!0x3c000 = prob;
context_index?0x3c000 = prob;
bit
}