Tweak the compression presets -0 .. -5.

"Extreme" mode might need some further tweaking still.
Docs were not updated yet.

diff --git a/src/liblzma/lzma/lzma_encoder_presets.c b/src/liblzma/lzma/lzma_encoder_presets.c
index c4c9c146f559104c8e1ba519ab2a040cf18bbb21..2aa8fd03e97e79f8af43e193bd4437d81579efc6 100644 (file)
--- a/src/liblzma/lzma/lzma_encoder_presets.c
+++ b/src/liblzma/lzma/lzma_encoder_presets.c
@@ -23,9 +23,6 @@ lzma_lzma_preset(lzma_options_lzma *options, uint32_t preset)
        if (level > 9 || (flags & ~supported_flags))
                return true;
 
-       const uint32_t dict_shift = level <= 1 ? 16 : level + 17;
-       options->dict_size = UINT32_C(1) << dict_shift;
-
        options->preset_dict = NULL;
        options->preset_dict_size = 0;
 
@@ -33,19 +30,31 @@ lzma_lzma_preset(lzma_options_lzma *options, uint32_t preset)
        options->lp = LZMA_LP_DEFAULT;
        options->pb = LZMA_PB_DEFAULT;
 
-       options->mode = level <= 2 ? LZMA_MODE_FAST : LZMA_MODE_NORMAL;
+       options->dict_size = UINT32_C(1) << (uint8_t []){
+                       18, 20, 21, 22, 22, 23, 23, 24, 25, 26 }[level];
 
-       options->nice_len = level == 0 ? 8 : level <= 5 ? 32 : 64;
-       options->mf = level <= 1 ? LZMA_MF_HC3 : level <= 2 ? LZMA_MF_HC4
-                       : LZMA_MF_BT4;
-       options->depth = 0;
+       if (level <= 3) {
+               options->mode = LZMA_MODE_FAST;
+               options->mf = level == 0 ? LZMA_MF_HC3 : LZMA_MF_HC4;
+               options->nice_len = level <= 1 ? 128 : 273;
+               options->depth = (uint8_t []){ 4, 8, 24, 48 }[level];
+       } else {
+               options->mode = LZMA_MODE_NORMAL;
+               options->mf = LZMA_MF_BT4;
+               options->nice_len = level == 4 ? 16 : level == 5 ? 32 : 64;
+               options->depth = 0;
+       }
 
        if (flags & LZMA_PRESET_EXTREME) {
                options->lc = 4; // FIXME?
                options->mode = LZMA_MODE_NORMAL;
                options->mf = LZMA_MF_BT4;
-               options->nice_len = 273;
-               options->depth = 512;
+               if (level == 3 || level == 5) {
+                       options->nice_len = 192;
+               } else {
+                       options->nice_len = 273;
+                       options->depth = 512;
+               }
        }
 
        return false;