git subrepo pull --force deps/lightrec

[pcsx_rearmed.git] / deps / lightning / doc / body.texi

diff --git a/deps/lightning/doc/body.texi b/deps/lightning/doc/body.texi
index 51c08d3..1d8d277 100644 (file)
--- a/deps/lightning/doc/body.texi
+++ b/deps/lightning/doc/body.texi
@@ -89,7 +89,11 @@ assembles machine instructions without further tests.
 @node Installation
 @chapter Configuring and installing @lightning{}
 
-The first thing to do to use @lightning{} is to configure the
+Here we will assume that your system already has the dependencies
+necessary to build @lightning{}. For more on dependencies, see
+@lightning{}'s @file{README-hacking} file.
+
+The first thing to do to build @lightning{} is to configure the
 program, picking the set of macros to be used on the host
 architecture; this configuration is automatically performed by
 the @file{configure} shell script; to run it, merely type:
@@ -368,6 +372,14 @@ htonr    _us _ui _ul @r{Host-to-network (big endian) order}
 ntohr    _us _ui _ul @r{Network-to-host order }
 @end example
 
+@code{bswapr} can be used to unconditionally byte-swap an operand.
+On little-endian architectures, @code{htonr} and @code{ntohr} resolve
+to this.
+The @code{_ul} variant is only available in 64-bit architectures.
+@example
+bswapr    _us _ui _ul  01 = byte_swap(02)
+@end example
+
 @item Load operations
 @code{ld} accepts two operands while @code{ldx} accepts three;
 in both cases, the last can be either a register or an immediate
@@ -585,6 +597,12 @@ forward   (not specified)                @r{forward label}
 indirect  (not specified)                @r{special simple label}
 @end example
 
+The following instruction is used to specify a minimal alignment for
+the next instruction, usually with a label:
+@example
+align     (not specified)                @r{align code}
+@end example
+
 @code{label} is normally used as @code{patch_at} argument for backward
 jumps.
 
@@ -637,6 +655,38 @@ that automatically binds the implicit label added by @code{patch} with
 the @code{movi}, but on some special conditions it is required to create
 an "unbound" label.
 
+@code{align} is useful for creating multiple entry points to a
+(trampoline) function that are all accessible through a single
+function pointer.  @code{align} receives an integer argument that
+defines the minimal alignment of the address of a label directly
+following the @code{align} instruction.  The integer argument must be
+a power of two and the effective alignment will be a power of two no
+less than the argument to @code{align}.  If the argument to
+@code{align} is 16 or more, the effective alignment will match the
+specified minimal alignment exactly.
+
+@example
+          jit_node_t *forward, *label1, *label2, *jump;
+          unsigned char *addr1, *addr2;
+forward = jit_forward();
+          jit_align(16);
+label1  = jit_indirect();                @rem{/* first entry point */}
+jump    = jit_jmpi();                    @rem{/* jump to first handler */}
+          jit_patch_at(jump, forward);
+          jit_align(16);
+label2  = jit_indirect();                @rem{/* second entry point */}
+          ...                            @rem{/* second handler */}
+          jit_jmpr(...);
+          jit_link(forward);
+          ...                            @rem{/* first handler /*}
+          jit_jmpr(...);
+          ...
+          jit_emit();
+          addr1 = jit_address(label1);
+          addr2 = jit_address(label2);
+          assert(addr2 - addr1 == 16);   @rem{/* only one of the addresses needs to be remembered */}
+@end example
+
 @item Function prolog
 
 These macros are used to set up a function prolog.  The @code{allocai}
@@ -878,6 +928,34 @@ to save and load the values when making function calls.
 @code{pointer_p} expects a pointer argument, and will return non
 zero if the pointer is inside the generated jit code. Must be
 called after @code{jit_emit} and before @code{jit_destroy_state}.
+
+@item Atomic operations
+Only compare-and-swap is implemented. It accepts four operands;
+the second can be an immediate.
+
+The first argument is set with a boolean value telling if the operation
+did succeed.
+
+Arguments must be different, cannot use the result register to also pass
+an argument.
+
+The second argument is the address of a machine word.
+
+The third argument is the old value.
+
+The fourth argument is the new value.
+
+@example
+casr                                  01 = (*O2 == O3) ? (*O2 = O4, 1) : 0
+casi                                  01 = (*O2 == O3) ? (*O2 = O4, 1) : 0
+@end example
+
+If value at the address in the second argument is equal to the third
+argument, the address value is atomically modified to the value of the
+fourth argument and the first argument is set to a non zero value.
+
+If the value at the address in the second argument is not equal to the
+third argument nothing is done and the first argument is set to zero.
 @end table
 
 @node GNU lightning examples