From ae461a87091b2e45d547c573431c6fa98c68c33a Mon Sep 17 00:00:00 2001
From: Sijmen Schoon <me@sijmenschoon.nl>
Date: Sun, 6 Dec 2020 18:07:35 +0100
Subject: [PATCH] C64

---
 .gitignore     |   2 +
 c64/main.asm   | 137 +++++++++++++++++++++++++++++++++++++
 c64/main.prg   | Bin 0 -> 47938 bytes
 c64/math.inc   |  94 +++++++++++++++++++++++++
 c64/screen.asm | 182 +++++++++++++++++++++++++++++++++++++++++++++++++
 5 files changed, 415 insertions(+)
 create mode 100644 .gitignore
 create mode 100644 c64/main.asm
 create mode 100644 c64/main.prg
 create mode 100644 c64/math.inc
 create mode 100644 c64/screen.asm

diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..9da9ebc
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,2 @@
+rust/target
+c64/*.vs
diff --git a/c64/main.asm b/c64/main.asm
new file mode 100644
index 0000000..0f578b5
--- /dev/null
+++ b/c64/main.asm
@@ -0,0 +1,137 @@
+// vim: filetype=kickass
+#import "math.inc"
+
+* = $0801                               // BASIC start address (#2049)
+.byte $0d,$08,$dc,$07,$9e,$20,$34,$39   // BASIC loader to start at $c000...
+.byte $31,$35,$32,$00,$00,$00           // puts BASIC line 2012 SYS 49152
+
+* = $c000
+
+.const SCREEN_RAM = $0400
+.const COLOR_RAM = $d800
+
+.const kernal_scinit = $ff81
+.const kernal_chrout = $ffd2
+.const kernal_write_byte = $e716
+
+.const zp_temp = $02
+.const cursor_pointer_lo = $05
+.const cursor_pointer_hi = $06
+
+//
+// main
+//
+main:
+    jsr clear_screen
+
+    // lda #0
+    // sta $d020
+    // sta $d021
+
+    jsr day01
+
+!loop:
+    // inc $d020
+    jmp !loop-
+
+string:
+    .text "The quick brown newline jumped over the lazy dog."
+    .byte '\n'
+    .byte 0
+
+string_cr:
+    .text "The quick brown carriage return jumped over the lazy dog."
+    .byte '\r'
+    .byte 0
+
+
+day01:
+    lda #<str_input
+    sta $03
+    lda #>str_input
+    sta $04
+    jsr write_string
+
+    lda #<day01_input
+    sta $03
+    lda #>day01_input
+    sta $04
+    jsr write_string
+
+    lda #<str_converted
+    sta $03
+    lda #>str_converted
+    sta $04
+    jsr write_string
+
+
+    lda #<day01_input
+    sta $03
+    lda #>day01_input
+    sta $04
+
+.break
+    ldy #0
+
+!line:
+    lda #0
+    sta $22
+    sta $23
+
+!digit:
+    lda ($03), y
+    cmp #'\n'
+    beq !break+
+
+    i16_mul10($22, $23)
+
+    lda ($03), y
+
+    sec
+    sbc #'0'
+
+    i16_i8_add_a($22, $23)
+
+    iny
+    jmp !digit-
+
+!break:
+    sty $24
+
+    lda $23
+    jsr print_hex_0x
+    lda $22
+    jsr print_hex
+
+    jsr print_newline
+    jsr print_carriage_return
+
+    ldy $24
+    iny
+
+    lda ($03), y
+    bne !line-
+
+!done:
+    rts
+
+
+day01_input:
+    .import text "../rust/inputs/day01_example"
+    .byte 0
+
+str_input:
+    .text "# Input"
+    .byte '\n', 0
+
+str_converted:
+    .byte '\n'
+    .text "# Converted"
+    .byte '\n', 0
+
+
+buffer:
+    .fill $0100, 0
+
+
+#import "screen.asm"
diff --git a/c64/main.prg b/c64/main.prg
new file mode 100644
index 0000000000000000000000000000000000000000..a67a645c46b0a8d1346e15bfb8d5bbba339db280
GIT binary patch
literal 47938
zcmeIwziX307{Kw%o7|fpHc1<j=GDdHeM`|nX_6*sMy(bM8T|u-5Frk(ods_!xW0>&
z;tP4lI0$YrUDDx&jB3Qu(k;8Rc(HV7i?bcR2lw9d-aW^A@8`K#Dx3O|e6KcJm3mds
z5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0
z009ILKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{
z1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0009IL
zKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~0R#|0009ILKmY**5I_I{1Q0*~
z0R#|0009ILKmY**5I_I{1Q56(0_wq7?T$M3=y^)2l~Ou>OId|{Ij3^6yp+yKl__PH
zWkTgwWkD59&Qk2oZI#F;A4cNpmUygCNXL>=6=bng$o+fko(NZUJp7^)>f<>4ZNkxc
zc=y`uz6gbOwKt3(Me~~Nu6u#2PXkY%E#gIY0=IXn-N5UeEz-75Hk_WT-FMb6Z_*iz
z-mV3n`Z*3<WgV&)WA%FcVQn&uPY2yfvs#H-%~n)vG@@#&6*ZdmsIpmaM8Z?ga?7P+
zBqC33=X2)Yi!u@2kdpnsW0+znUnG1XePR0|=^rP<m@mHi;+rqN`(oxF&nDBEshA8C
z+78Qm&a}G~$o@SoO+9QA+b3pW$9^d<dLXsc?q_?}t9IKw{*KzpWSpL*r7hR(i|zz=
z-|X!kh<!1P&%L9)xnu6c${QKRoSr=Y!ld(Qd|u^6)YaC32sbWegwCbcz+{*Mm^S!a
cIlQuTKYwkqyHTmu%pGZNwH`g*e)4qZ4^F?W*Z=?k

literal 0
HcmV?d00001

diff --git a/c64/math.inc b/c64/math.inc
new file mode 100644
index 0000000..7bae2dc
--- /dev/null
+++ b/c64/math.inc
@@ -0,0 +1,94 @@
+// vim: filetype=kickass
+
+.macro i8_div5_a() {
+    sta zp_temp
+    lsr
+    adc #13
+    adc zp_temp
+    ror
+    lsr
+    lsr
+    adc zp_temp
+    ror
+    adc zp_temp
+    ror
+    lsr
+    lsr
+}
+
+.macro i16_div8(lo, hi) {
+    lsr cursor_pointer_hi
+    ror cursor_pointer_lo
+
+    lsr cursor_pointer_hi
+    ror cursor_pointer_lo
+
+    lsr cursor_pointer_hi
+    ror cursor_pointer_lo
+}
+
+.macro i8_mul5_a() {
+    sta zp_temp
+    asl
+    asl
+    clc
+    adc zp_temp
+}
+
+// Destroys: lo, hi
+.macro i16_mul2(lo, hi) {
+    asl lo
+    rol hi
+}
+
+// Destroys: lo, hi
+.macro i16_mul4(lo, hi) {
+    i16_mul2(lo, hi)
+    i16_mul2(lo, hi)
+}
+
+// Destroys: lo, hi
+.macro i16_mul8(lo, hi) {
+    i16_mul4(lo, hi)
+    i16_mul2(lo, hi)
+}
+
+// Destroys: a, lo, hi, $fd, $fe
+.macro i16_mul10(lo, hi) {
+    i16_mul2(lo, hi)
+
+    lda lo
+    sta $fd
+    lda hi
+    sta $fe
+
+    i16_mul4(lo, hi)
+    i16_i16_add(lo, hi, $fd, $fe)
+}
+
+// Destroys: a, dst_lo, dst_hi
+.macro i16_i8_add_a(dst_lo, dst_hi) {
+    clc
+    adc dst_lo
+    sta dst_lo
+    bcc !cc+
+    inc dst_hi
+!cc:
+}
+
+// Destroys: a, dst_lo, dst_hi
+.macro i16_i16_add(dst_lo, dst_hi, src_lo, src_hi) {
+    clc
+    lda dst_lo
+    adc src_lo
+    sta dst_lo
+    lda dst_hi
+    adc src_hi
+    sta dst_hi
+}
+
+// Destroys: a, dst_lo, dst_hi
+.macro i16_inc(lo, hi) {
+    lda #1
+    i16_i8_add_a(lo, hi)
+}
diff --git a/c64/screen.asm b/c64/screen.asm
new file mode 100644
index 0000000..458ba4e
--- /dev/null
+++ b/c64/screen.asm
@@ -0,0 +1,182 @@
+// vim: filetype=kickass
+
+//
+// clear_screen
+//
+// Destroys: a, y
+//
+clear_screen:
+    ldy #0
+
+!loop:
+    lda #' '
+    sta SCREEN_RAM, y
+    sta SCREEN_RAM + $0100, y
+    sta SCREEN_RAM + $0200, y
+    sta SCREEN_RAM + $0300, y
+    sta SCREEN_RAM + $03e7, y
+
+    lda #1
+    sta COLOR_RAM, y
+    sta COLOR_RAM + $0100, y
+    sta COLOR_RAM + $0200, y
+    sta COLOR_RAM + $0300, y
+    sta COLOR_RAM + $03e7, y
+
+    iny
+    bne !loop-
+
+    lda #<SCREEN_RAM
+    sta cursor_pointer_lo
+    lda #>SCREEN_RAM
+    sta cursor_pointer_hi
+
+    lda #23
+    sta $d018
+
+    rts
+
+
+//
+// print_carriage_return
+//
+// Input:
+//  - cursor_pointer_{lo,hi} - Cursor pointer.
+//
+// Destroys: a, zp_temp
+//
+print_newline:
+    sec
+    lda $05
+    adc #40
+    sta cursor_pointer_lo
+    bcc !done+
+    inc cursor_pointer_hi
+
+!done:
+    rts
+
+
+//
+// print_carriage_return
+//
+// Input:
+//  - cursor_pointer_{lo,hi} - Cursor pointer.
+//
+// Destroys: a, zp_temp
+//
+print_carriage_return:
+    // Subtract SCREEN_RAM from cursor pointer
+    sec
+    lda cursor_pointer_hi
+    sbc #>SCREEN_RAM
+    sta cursor_pointer_hi
+
+    // Divide the cursor position by 40 (one row)
+    i16_div8(cursor_pointer_lo, cursor_pointer_hi)
+
+    // At this point, the pointer fits in a 8-bit register
+    lda cursor_pointer_lo
+    i8_div5_a()
+
+    // Multiply it by 40 again
+    i8_mul5_a()
+    sta cursor_pointer_lo
+
+    i16_mul8(cursor_pointer_lo, cursor_pointer_hi)
+
+    // Add SCREEN_RAM back
+    clc
+    lda cursor_pointer_hi
+    adc #>SCREEN_RAM
+    sta cursor_pointer_hi
+
+    rts
+
+
+//
+// write_string
+//
+// Input:
+//  - $03-$04 - Pointer to null-terminated string.
+//  - $05-$06 - Cursor pointer.
+//
+// Destroys: a, x, y
+//
+write_string:
+    ldx #0
+    ldy #0
+
+!loop:
+    lda ($03), y
+    beq !done+
+
+    cmp #'\r'
+    beq !carriage_return+
+    cmp #'\n'
+    beq !newline+
+
+    sta (cursor_pointer_lo, x)
+
+    i16_inc(cursor_pointer_lo, cursor_pointer_hi)
+
+    iny
+    jmp !loop-
+
+!newline:
+    jsr print_newline
+
+!carriage_return:
+    jsr print_carriage_return
+
+    iny
+    jmp !loop-
+
+!done:
+    rts
+
+
+print_hex_0x:
+    sta zp_temp
+
+    ldx #0
+
+    lda #'0'
+    sta (cursor_pointer_lo, x)
+    i16_inc(cursor_pointer_lo, cursor_pointer_hi)
+
+    lda #'x'
+    sta (cursor_pointer_lo, x)
+    i16_inc(cursor_pointer_lo, cursor_pointer_hi)
+
+    lda zp_temp
+
+    // fallthrough
+
+print_hex:
+    ldx #0
+    sta zp_temp
+
+    lsr
+    lsr
+    lsr
+    lsr
+    tay
+
+    lda !hex_chars+, y
+    sta (cursor_pointer_lo, x)
+    i16_inc(cursor_pointer_lo, cursor_pointer_hi)
+
+    lda zp_temp
+    and #$0f
+    tay
+
+    lda !hex_chars+, y
+    sta (cursor_pointer_lo, x)
+    i16_inc(cursor_pointer_lo, cursor_pointer_hi)
+
+    rts
+
+!hex_chars:
+    .text "0123456789ABCDEF"
+