DynASM/PPC: Add support for parameterized shifts/masks.

dynasm/dasm_ppc.h

@@ -21,7 +21,7 @@ enum {
   /* The following actions need a buffer position. */
   DASM_ALIGN, DASM_REL_LG, DASM_LABEL_LG,
   /* The following actions also have an argument. */
-  DASM_REL_PC, DASM_LABEL_PC, DASM_IMM,
+  DASM_REL_PC, DASM_LABEL_PC, DASM_IMM, DASM_IMMSH,
   DASM__MAX
 };
 
@@ -244,6 +244,10 @@ void dasm_put(Dst_DECL, int start, ...)
 #endif
 	b[pos++] = n;
 	break;
+      case DASM_IMMSH:
+	CK((n >> 6) == 0, RANGE_I);
+	b[pos++] = n;
+	break;
       }
     }
   }
@@ -299,7 +303,7 @@ int dasm_link(Dst_DECL, size_t *szp)
 	case DASM_ALIGN: ofs -= (b[pos++] + ofs) & (ins & 255); break;
 	case DASM_REL_LG: case DASM_REL_PC: pos++; break;
 	case DASM_LABEL_LG: case DASM_LABEL_PC: b[pos++] += ofs; break;
-	case DASM_IMM: pos++; break;
+	case DASM_IMM: case DASM_IMMSH: pos++; break;
 	}
       }
       stop: (void)0;
@@ -366,6 +370,9 @@ int dasm_encode(Dst_DECL, void *buffer)
 	case DASM_IMM:
 	  cp[-1] |= (n & ((1<<((ins>>5)&31))-1)) << (ins&31);
 	  break;
+	case DASM_IMMSH:
+	  cp[-1] |= (ins & 1) ? ((n&31)<<11)|((n&32)>>4) : ((n&31)<<6)|(n&32);
+	  break;
 	default: *cp++ = ins; break;
 	}
       }

dynasm/dasm_ppc.lua

@@ -41,7 +41,7 @@ local wline, werror, wfatal, wwarn
 local action_names = {
   "STOP", "SECTION", "ESC", "REL_EXT",
   "ALIGN", "REL_LG", "LABEL_LG",
-  "REL_PC", "LABEL_PC", "IMM",
+  "REL_PC", "LABEL_PC", "IMM", "IMMSH"
 }
 
 -- Maximum number of section buffer positions for dasm_put().
@@ -1482,8 +1482,8 @@ local function parse_shiftmask(imm, isshift)
   local n = tonumber(imm)
   if n then
     if shr(n, 6) == 0 then
-      local lsb = band(imm, 31)
-      local msb = imm - lsb
+      local lsb = band(n, 31)
+      local msb = n - lsb
       return isshift and (shl(lsb, 11)+shr(msb, 4)) or (shl(lsb, 6)+msb)
     end
     werror("out of range immediate `"..imm.."'")
@@ -1491,7 +1491,8 @@ local function parse_shiftmask(imm, isshift)
 	 match(imm, "^([%w_]+):(r[1-3]?[0-9])$") then
     werror("expected immediate operand, got register")
   else
-    werror("NYI: parameterized 64 bit shift/mask")
+    waction("IMMSH", isshift and 1 or 0, imm)
+    return 0;
   end
 end