shithub: rgbds

--- a/src/asm/rgbasm.5

+++ b/src/asm/rgbasm.5

@@ -38,7 +38,8 @@

 John: ld a,87 ;Weee

.Ed

.Pp

-All reserved keywords (pseudo‐ops, mnemonics, registers etc.) are case‐insensitive, all identifiers (symbol names) are case-sensitive.

+All reserved keywords (pseudo‐ops, mnemonics, registers, etc.) are case‐insensitive;

+all identifiers (symbol names) are case-sensitive.

.Pp

 Comments are used to give humans information about the code, such as explanations.

 The assembler

@@ -204,18 +205,22 @@

 delim off

.EN

.Pp

+The trigonometry functions (

+.Ic SIN ,

+.Ic COS ,

+.Ic TAN ,

+etc) are defined in terms of a circle divided into 65535.0 degrees.

+.Pp

 These functions are useful for automatic generation of various tables.

-Example: assuming a circle has 65536.0 degrees, and sine values are in range

-.Bq -1.0 ;\ 1.0 :

+For example:

 .Bd -literal -offset indent

-;\ --

-;\ -- Generate a 256-byte sine table with values between 0 and 128

-;\ --

+; Generate a 256-byte sine table with values in the range [0, 128]

+; (shifted and scaled from the range [-1.0, 1.0])

 ANGLE = 0.0

-      REPT 256

-      db MUL(64.0, SIN(ANGLE) + 1.0) >> 16

-ANGLE = ANGLE + 256.0 ; 256 = 65536 / table_len, with table_len = 256

-      ENDR

+    REPT 256

+        db (MUL(64.0, SIN(ANGLE)) + 64.0) >> 16

+ANGLE = ANGLE + 256.0 ; 256.0 = 65536 degrees / 256 entries

+    ENDR

.Ed

 .Ss String Expressions

 The most basic string expression is any number of characters contained in double quotes

@@ -238,7 +243,7 @@

 .It Ql \[rs]t Ta Tab ($09)

 .It Qo \[rs]1 Qc \[en] Qo \[rs]9 Qc Ta Macro argument (Only in the body of a macro; see Sx Invoking macros )

 .It Ql \[rs]# Ta All Dv _NARG No macro arguments, separated by commas (Only in the body of a macro)

-.It Ql \[rs]@ Ta Label name suffix (Only in the body of macros and REPTs)

+.It Ql \[rs]@ Ta Label name suffix (Only in the body of a macro or a Ic REPT No block)

.El

 (Note that some of those can be used outside of strings, when noted further in this document.)

.Pp

@@ -362,13 +367,13 @@

 .Bl -column "STRSUB(str, pos, len)"

 .It Sy Name Ta Sy Operation

 .It Fn STRLEN str Ta Returns the number of characters in Ar str .

-.It Fn STRCAT str1 str2 Ta Appends Ar str2 No to Ar str1 .

+.It Fn STRCAT strs... Ta Concatenates Ar strs .

 .It Fn STRCMP str1 str2 Ta Returns -1 if Ar str1 No is alphabetically lower than Ar str2 No , zero if they match, 1 if Ar str1 No is greater than Ar str2 .

 .It Fn STRIN str1 str2 Ta Returns the first position of Ar str2 No in Ar str1 No or zero if it's not present Pq first character is position 1 .

 .It Fn STRRIN str1 str2 Ta Returns the last position of Ar str2 No in Ar str1 No or zero if it's not present Pq first character is position 1 .

 .It Fn STRSUB str pos len Ta Returns a substring from Ar str No starting at Ar pos Po first character is position 1 Pc and Ar len No characters long.

-.It Fn STRUPR str Ta Converts all characters in Ar str No to capitals and returns the new string.

-.It Fn STRLWR str Ta Converts all characters in Ar str No to lower case and returns the new string.

+.It Fn STRUPR str Ta Returns Ar str No with all letters in uppercase.

+.It Fn STRLWR str Ta Returns Ar str No with all letters in lowercase.

 .It Fn STRFMT fmt args... Ta Returns the string Ar fmt No with each

 .Ql %spec

 pattern replaced by interpolating the format

@@ -1530,11 +1535,12 @@

 .Ic REPT

 to generate tables on the fly:

 .Bd -literal -offset indent

-; Generate a 256-byte sine table with values between 0 and 128

+; Generate a 256-byte sine table with values in the range [0, 128]

+; (shifted and scaled from the range [-1.0, 1.0])

 ANGLE = 0.0

     REPT 256

         db (MUL(64.0, SIN(ANGLE)) + 64.0) >> 16

-ANGLE = ANGLE + 256.0

+ANGLE = ANGLE + 256.0 ; 256.0 = 65536 degrees / 256 entries

     ENDR

.Ed

.Pp