updated programs/README.md, to introduce compilation variables

make it possible to enable/disable features individually

programs/Makefile

@@ -138,19 +138,16 @@ all: zstd
 
 $(ZSTDDECOMP_O): CFLAGS += $(ALIGN_LOOP)
 
-zstd-nogz zstd xzstd zstd4 xzstd4 : CPPFLAGS += $(THREAD_CPP)
+zstd xzstd zstd4 xzstd4 : CPPFLAGS += $(THREAD_CPP) $(ZLIBCPP)
-zstd-nogz zstd xzstd zstd4 xzstd4 : LDFLAGS += $(THREAD_LD)
+zstd xzstd zstd4 xzstd4 : LDFLAGS += $(THREAD_LD) $(ZLIBLD)
-zstd xzstd zstd4 xzstd4 : CPPFLAGS += $(ZLIBCPP)
-zstd xzstd zstd4 xzstd4 : LDFLAGS += $(ZLIBLD)
 xzstd xzstd4 : CPPFLAGS += $(LZMACPP)
 xzstd xzstd4 : LDFLAGS += $(LZMALD)
 zstd4 xzstd4 : CPPFLAGS += $(LZ4CPP)
 zstd4 xzstd4 : LDFLAGS += $(LZ4LD)
-zstd-nogz : ZLIB_MSG := - gzip support is disabled
+zstd zstd4 : LZMA_MSG := - xz/lzma support is disabled
-zstd zstd-nogz zstd4 : LZMA_MSG := - xz/lzma support is disabled
+zstd xzstd : LZ4_MSG := - lz4 support is disabled
-zstd zstd-nogz xzstd : LZ4_MSG := - lz4 support is disabled
+zstd xzstd zstd4 xzstd4 : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
-zstd zstd-nogz xzstd zstd4 xzstd4 : CPPFLAGS += -DZSTD_LEGACY_SUPPORT=$(ZSTD_LEGACY_SUPPORT)
+zstd xzstd zstd4 xzstd4 : $(ZSTDLIB_FILES) zstdcli.o fileio.o bench.o datagen.o dibio.o
-zstd zstd-nogz xzstd zstd4 xzstd4 : $(ZSTDLIB_FILES) zstdcli.o fileio.o bench.o datagen.o dibio.o
 	@echo "$(THREAD_MSG)"
 	@echo "$(ZLIB_MSG)"
 	@echo "$(LZMA_MSG)"
@@ -170,7 +167,6 @@ ifneq (,$(filter Windows%,$(OS)))
 endif
 	$(CC) -m32 $(FLAGS) $^ $(RES32_FILE) -o $@$(EXT)
 
-
 zstd-nolegacy : clean_decomp_o
 	$(MAKE) zstd ZSTD_LEGACY_SUPPORT=0
 
@@ -179,6 +175,12 @@ zstd-nomt : THREAD_LD :=
 zstd-nomt : THREAD_MSG := - multi-threading disabled
 zstd-nomt : zstd
 
+zstd-nogz : ZLIBCPP :=
+zstd-nogz : ZLIBLD :=
+zstd-nogz : ZLIB_MSG := - gzip support is disabled
+zstd-nogz : zstd
+
+
 zstd-pgo : MOREFLAGS = -fprofile-generate
 zstd-pgo : clean zstd
 	./zstd -b19i1 $(PROFILE_WITH)

programs/README.md

@@ -11,6 +11,27 @@ There are however other Makefile targets that create different variations of CLI
 - `zstd-decompress` : decompressor-only version of CLI; without dictionary builder, benchmark, and support for decompression of legacy zstd versions
 
 
+#### Compilation variables
+`zstd` tries to detect and use the following features automatically :
+
+- __HAVE_THREAD__ : multithreading is automatically enabled when `pthread` is detected.
+  It's possible to disable multithread support, by either compiling `zstd-nomt` target or using HAVE_THREAD=0 variable.
+  Example : make zstd HAVE_THREAD=0
+  It's also possible to force compilation with multithread support, using HAVE_THREAD=1.
+  In which case, linking stage will fail if `pthread` library cannot be found.
+  This might be useful to prevent silent feature disabling.
+
+- __HAVE_ZLIB__ : `zstd` can compress and decompress files in `.gz` format.
+  This is done through command `--format=gzip`.
+  Alternatively, symlinks named `gzip` or `gunzip` will mimic intended behavior.
+  .gz support is automatically enabled when `zlib` library is detected at build time.
+  It's possible to disable .gz support, by either compiling `zstd-nogz` target or using HAVE_ZLIB=0 variable.
+  Example : make zstd HAVE_ZLIB=0
+  It's also possible to force compilation with zlib support, using HAVE_ZLIB=1.
+  In which case, linking stage will fail if `zlib` library cannot be found.
+  This might be useful to prevent silent feature disabling.
+
+
 #### Aggregation of parameters
 CLI supports aggregation of parameters i.e. `-b1`, `-e18`, and `-i1` can be joined into `-b1e18i1`.
 
@@ -35,7 +56,6 @@ Usage of the dictionary builder and created dictionaries with CLI:
 3. Decompress with the dictionary: `zstd --decompress FILE.zst -D dictionaryName`
 
 
-
 #### Benchmark in Command Line Interface
 CLI includes in-memory compression benchmark module for zstd.
 The benchmark is conducted using given filenames. The files are read into memory and joined together.
@@ -48,7 +68,6 @@ One can select compression levels starting from `-b` and ending with `-e`.
 The `-i` parameter selects minimal time used for each of tested levels.
 
 
-
 #### Usage of Command Line Interface
 The full list of options can be obtained with `-h` or `-H` parameter:
 ```
@@ -62,33 +81,40 @@ Arguments :
  -d     : decompression
  -D file: use `file` as Dictionary
  -o file: result stored into `file` (only if 1 input file)
- -f     : overwrite output without prompting
+ -f     : overwrite output without prompting and (de)compress links
 --rm    : remove source file(s) after successful de/compression
  -k     : preserve source file(s) (default)
  -h/-H  : display help/long help and exit
 
 Advanced arguments :
  -V     : display Version number and exit
- -v     : verbose mode; specify multiple times to increase log level (default:2)
+ -v     : verbose mode; specify multiple times to increase verbosity
  -q     : suppress warnings; specify twice to suppress errors too
  -c     : force write to standard output, even if it is the console
- -r     : operate recursively on directories
 --ultra : enable levels beyond 19, up to 22 (requires more memory)
+ -T#    : use # threads for compression (default:1)
+ -B#    : select size of each job (default:0==automatic)
 --no-dictID : don't write dictID into header (dictionary compression)
 --[no-]check : integrity check (default:enabled)
+ -r     : operate recursively on directories
+--format=gzip : compress files to the .gz format
 --test  : test compressed file integrity
---[no-]sparse : sparse mode (default:enabled on file, disabled on stdout)
+--[no-]sparse : sparse mode (default:disabled)
+ -M#    : Set a memory usage limit for decompression
+--      : All arguments after "--" are treated as files
 
 Dictionary builder :
 --train ## : create a dictionary from a training set of files
+--train-cover[=k=#,d=#,steps=#] : use the cover algorithm with optional args
+--train-legacy[=s=#] : use the legacy algorithm with selectivity (default: 9)
  -o file : `file` is dictionary name (default: dictionary)
---maxdict ## : limit dictionary to specified size (default : 112640)
+--maxdict=# : limit dictionary to specified size (default : 112640)
- -s#    : dictionary selectivity level (default: 9)
+--dictID=# : force dictionary ID to specified value (default: random)
---dictID ## : force dictionary ID to specified value (default: random)
 
 Benchmark arguments :
  -b#    : benchmark file(s), using # compression level (default : 1)
  -e#    : test all compression levels from -bX to # (default: 1)
  -i#    : minimum evaluation time in seconds (default : 3s)
  -B#    : cut file into independent blocks of size # (default: no block)
- ```
+--priority=rt : set process priority to real-time
+```