Fix sign bug in read_i32 on 64-bit ocaml

ocaml-batteries-team · Feb 16, 2010 · dac9f98 · dac9f98
1 parent 9693d99
commit dac9f98
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Showing 2 changed files with 8 additions and 4 deletions.
diff --git a/src/batIO.ml b/src/batIO.ml
@@ -200,15 +200,17 @@ let read_i16 i =
 	else
 		n
 
+let fix = lnot 0x7FFFFFFF (* -:) *)
+
 let read_i32 ch =
 	let ch4 = read_byte ch in
 	let ch3 = read_byte ch in
 	let ch2 = read_byte ch in
 	let ch1 = read_byte ch in
-	if ch4 land 128 <> 0 then begin
+	if ch4 land 128 <> 0 then begin (* negative number *)
 		if ch4 land 64 = 0 then raise (Overflow "read_i32");
-		ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor ((ch4 land 127) lsl 24)
-	end else begin
+		(ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor ((ch4 land 127) lsl 24)) lor fix (* FIX HERE *)
+	end else begin (*positive number*)
 		if ch4 land 64 <> 0 then raise (Overflow "read_i32");
 		ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor (ch4 lsl 24)
 	end

diff --git a/src/batInnerIO.ml b/src/batInnerIO.ml
@@ -519,14 +519,16 @@ let read_i16 i =
 	else
 		n
 
+let fix = lnot 0x7FFFFFFF (* -:) *)
+
 let read_i32 ch =
 	let ch1 = read_byte ch in
 	let ch2 = read_byte ch in
 	let ch3 = read_byte ch in
 	let ch4 = read_byte ch in
 	if ch4 land 128 <> 0 then begin
 		if ch4 land 64 = 0 then raise (Overflow "read_i32");
-		ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor ((ch4 land 127) lsl 24)
+	        (ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor ((ch4 land 127) lsl 24)) lor fix (* FIX HERE *)
 	end else begin
 		if ch4 land 64 <> 0 then raise (Overflow "read_i32");
 		ch1 lor (ch2 lsl 8) lor (ch3 lsl 16) lor (ch4 lsl 24)