SXEmacs Lisp Reference Manual: CCL Expressions

66.7.3 CCL Expressions

CCL, unlike Lisp, uses infix expressions. The simplest CCL expressions consist of a single operand, either a register (one of r0, ..., r0) or an integer. Complex expressions are lists of the form ( expression operator operand ). Unlike C, assignments are not expressions.

In the following table, X is the target resister for a set. In subexpressions, this is implicitly r7. This means that >8, //, de-sjis, and en-sjis cannot be used freely in subexpressions, since they return parts of their values in r7. Y may be an expression, register, or integer, while Z must be a register or an integer.

Name	Operator	Code	C-like Description
CCL_PLUS	`+`	0x00	X = Y + Z
CCL_MINUS	`-`	0x01	X = Y - Z
CCL_MUL	`*`	0x02	X = Y * Z
CCL_DIV	`/`	0x03	X = Y / Z
CCL_MOD	`%`	0x04	X = Y % Z
CCL_AND	`&`	0x05	X = Y & Z
CCL_OR	`\|`	0x06	X = Y \| Z
CCL_XOR	`^`	0x07	X = Y ^ Z
CCL_LSH	`<<`	0x08	X = Y << Z
CCL_RSH	`>>`	0x09	X = Y >> Z
CCL_LSH8	`<8`	0x0A	X = (Y << 8) \| Z
CCL_RSH8	`>8`	0x0B	X = Y >> 8, r[7] = Y & 0xFF
CCL_DIVMOD	`//`	0x0C	X = Y / Z, r[7] = Y % Z
CCL_LS	`<`	0x10	X = (X < Y)
CCL_GT	`>`	0x11	X = (X > Y)
CCL_EQ	`==`	0x12	X = (X == Y)
CCL_LE	`<=`	0x13	X = (X <= Y)
CCL_GE	`>=`	0x14	X = (X >= Y)
CCL_NE	`!=`	0x15	X = (X != Y)
CCL_ENCODE_SJIS	`en-sjis`	0x16	X = HIGHER_BYTE (SJIS (Y, Z))
			r[7] = LOWER_BYTE (SJIS (Y, Z)
CCL_DECODE_SJIS	`de-sjis`	0x17	X = HIGHER_BYTE (DE-SJIS (Y, Z))
			r[7] = LOWER_BYTE (DE-SJIS (Y, Z))

The CCL operators are as in C, with the addition of CCL_LSH8, CCL_RSH8, CCL_DIVMOD, CCL_ENCODE_SJIS, and CCL_DECODE_SJIS. The CCL_ENCODE_SJIS and CCL_DECODE_SJIS treat their first and second bytes as the high and low bytes of a two-byte character code. (SJIS stands for Shift JIS, an encoding of Japanese characters used by Microsoft. CCL_ENCODE_SJIS is a complicated transformation of the Japanese standard JIS encoding to Shift JIS. CCL_DECODE_SJIS is its inverse.) It is somewhat odd to represent the SJIS operations in infix form.