Added fixpoint sine and cosine functions.

git-svn-id: svn://svn.cc65.org/cc65/trunk@4399 b7a2c559-68d2-44c3-8de9-860c34a00d81

libsrc/common/Makefile

@@ -99,6 +99,9 @@ S_OBJS = 	_cwd.o          \
 		atexit.o  	\
 		atoi.o	  	\
 		calloc.o  	\
+                cc65_cos.o      \
+                cc65_sin.o      \
+                cc65_sintab.o   \
                 chdir.o         \
 		copydata.o	\
                 creat.o         \

libsrc/common/cc65_cos.s

@@ -0,0 +1,48 @@
+;
+; Fixed point cosine function.
+;
+; Returns the cosine for the given argument as angular degree.
+; Valid argument range is 0..360
+;
+;
+; Ullrich von Bassewitz, 2009-10-29
+;
+
+        .export         _cc65_cos
+
+        .import         _cc65_sin
+
+
+
+; ---------------------------------------------------------------------------
+;
+
+.code
+
+.proc   _cc65_cos         
+
+; cos(x) = sin(x+90)
+
+        clc
+        adc     #90
+        bcc     L1
+        inx
+
+; If x is now larger than 360, we need to subtract 360.
+
+L1:     cpx     #>360
+        bne     L2
+        cmp     #<360
+L2:     bcc     L4
+
+        sbc     #<360
+        bcs     L3
+        dex
+L3:     dex
+
+L4:     jmp     _cc65_sin
+
+
+.endproc
+
+

libsrc/common/cc65_sin.s

@@ -0,0 +1,113 @@
+;
+; Fixed point sine function.
+;
+; Returns the cosine for the given argument as angular degree.
+; Valid argument range is 0..360
+;
+;
+; Ullrich von Bassewitz, 2009-10-29
+;
+
+        .export         _cc65_sin
+
+        .import         _cc65_sintab
+
+
+; ---------------------------------------------------------------------------
+;
+
+.code
+
+.proc   _cc65_sin
+
+; If the high byte is non zero, argument is > 255
+
+        cpx     #0
+        bne     L3
+        cmp     #180
+        bcs     L4
+
+; 0..179°
+
+        cmp     #90
+        bcc     L1
+
+; 90..179°. Value is identical to sin(180-val). Carry is set on entry.
+;
+;       180-val := -val + 180.
+; With
+;       -val := (val ^ $FF) + 1
+; we get
+;       180-val = (val ^ $FF) + 1 + 180
+; Since carry is set, we can drop the "+ 1".
+;
+
+        eor     #$FF
+        adc     #180            ; 180-val
+
+; 0..89°. Values for 87..90° are actually 1.0. Since this format doesn't fit
+; into the table, we have to check for it manually.
+
+L1:     cmp     #87
+        bcc     L2
+
+; The value is 1.0
+
+        ldx     #>(1 << 8)
+        lda     #<(1 << 8)
+        rts
+
+; 0..86°. Read the value from the table.
+
+L2:     tay
+        ldx     #0
+        lda     _cc65_sintab,y
+        rts
+
+; 180..360°. sin(x) = -sin(x-180). Since the argument is in range 0..180
+; after the subtraction, we don't need to handle the high byte.
+
+L3:     sec
+L4:     sbc     #180
+
+        cmp     #90
+        bcc     L5
+
+; 270..360°. Value is identical to -sin(180-val). Carry is set on entry.
+;
+;       180-val := -val + 180.
+; With
+;       -val := (val ^ $FF) + 1
+; we get
+;       180-val = (val ^ $FF) + 1 + 180
+; Since carry is set, we can drop the "+ 1".
+;
+
+        eor     #$FF
+        adc     #180            ; 180-val
+
+; 180..269°. Values for 267..269° are actually -1.0. Since this format doesn't
+; fit into the table, we have to check for it manually.
+
+L5:     ldx     #$FF
+        cmp     #87
+        bcc     L6
+
+; The value is -1.0
+
+        lda     #<(-1 << 8)
+        rts
+
+; 180..266°. Read the value from the table. Carry is clear on entry.
+
+L6:     tay
+        txa                     ; A = $FF
+        eor     _cc65_sintab,y
+        adc     #1
+        bcc     L7
+        inx
+L7:     rts
+
+.endproc
+
+

libsrc/common/cc65_sintab.s

@@ -0,0 +1,24 @@
+;
+; Sinus table
+;
+; Ullrich von Bassewitz, 2009-10-29
+;
+
+        .export         _cc65_sintab
+
+
+; ---------------------------------------------------------------------------
+;
+
+.rodata
+
+_cc65_sintab:
+        .byte   $00, $04, $09, $0D, $12, $16, $1B, $1F, $24, $28
+        .byte   $2C, $31, $35, $3A, $3E, $42, $47, $4B, $4F, $53
+        .byte   $58, $5C, $60, $64, $68, $6C, $70, $74, $78, $7C
+        .byte   $80, $84, $88, $8B, $8F, $93, $96, $9A, $9E, $A1
+        .byte   $A5, $A8, $AB, $AF, $B2, $B5, $B8, $BB, $BE, $C1
+        .byte   $C4, $C7, $CA, $CC, $CF, $D2, $D4, $D7, $D9, $DB
+        .byte   $DE, $E0, $E2, $E4, $E6, $E8, $EA, $EC, $ED, $EF
+        .byte   $F1, $F2, $F3, $F5, $F6, $F7, $F8, $F9, $FA, $FB
+        .byte   $FC, $FD, $FE, $FE, $FF, $FF, $FF