Library improvements:

– random module
– ensure_mixedcase() function

docs/README.md

@@ -39,7 +39,13 @@
 
 * [`stdlib` module](stdlib/stdlib.md)
 
-* [Other cross-platform modules](stdlib/other.md)
+* [`string` module](stdlib/string.md)
+
+* [Modules for reading input devices](stdlib/input.md)
+
+* [Other cross-platform modules (`err`, `stdio`, `random`)](stdlib/other.md)
+
+* [Definitions available on only some platforms](stdlib/frequent.md)
 
 * [C64-only modules](stdlib/c64.md)
 

docs/index.md

@@ -43,7 +43,7 @@
 
 * [Modules for reading input devices](stdlib/input.md)
 
-* [Other cross-platform modules (`err`, `stdio`)](stdlib/other.md)
+* [Other cross-platform modules (`err`, `stdio`, `random`)](stdlib/other.md)
 
 * [Definitions available on only some platforms](stdlib/frequent.md)
 

docs/stdlib/other.md

@@ -14,6 +14,10 @@ Prints a string of length `len` located at address `str`.
 Prints a null-terminated string located at address `str`.  
 If the string is longer than 255 bytes, then the behaviour is undefined (might even crash).
 
+#### `void ensure_mixedcase()`
+
+On targets that have separate all-caps and mixed-case modes (like most Commodore machines), switches to the mixed-case mode.
+
 
 ## err
 
@@ -24,3 +28,29 @@ Standard error codes. All codes other than `err_ok` suggest that the last operat
 #### `error_number errno`
 
 The result of the last operation.
+
+
+## random
+
+A simple and reasonably fast random number generator. Not suitable for cryptographic or simulation uses.
+
+#### `word rand_seed`
+
+Random number generator state.
+
+#### `byte rand()`
+
+Get a random byte (0–255) and update the state of the generator.
+
+#### `void init_rand_seed()`
+
+Initializes the random number generator state.
+This may take a long time, even several frames, depending on the target.
+
+Current implementation:  
+
+* On C64, spends two frames reading noise data from the SID chip.
+
+* On Z80, reads the refresh register.
+
+* On all other targets, sets the seed to 1.

examples/crossplatform/fire.mfk

@@ -1,4 +1,6 @@
 
+import random
+
 array reverse_palette[256] align(256)
 
 #if CBM
@@ -119,53 +121,3 @@ void fire() {
         p += COLUMN_COUNT
     }
 }
-
-word rand_seed
-
-#if CPU_6502
-asm byte rand() {
-    ldx #8   
-    lda rand_seed+0
-__rand_loop:
-    asl     
-    rol rand_seed+1
-    bcc __no_eor
-    eor #$2D 
-__no_eor:
-    dex
-    bne __rand_loop
-    sta rand_seed+0
-    ? rts
-}
-#elseif CPU_Z80
-inline asm byte rand() {
-    ld b,8
-    ld hl,(rand_seed)
-__rand_loop:
-    add hl,hl
-    jp nc, __no_eor
-    ld a,l
-    xor $2D
-    ld l,a
-__no_eor:
-    djnz __rand_loop
-    ld (rand_seed),hl
-    ? ret
-}
-#endif
-
-#if CBM_64
-inline void init_rand_seed() {
-    poke($D40E, $ff)
-    poke($D40F, $ff)
-    poke($D412, $80)
-    while vic_raster != $70 {}
-    rand_seed.hi = peek($D41B)
-    while vic_raster != $40 {}
-    rand_seed.lo = peek($D41B)
-}
-#else
-inline void init_rand_seed() {
-    rand_seed = 1
-}
-#endif

examples/crossplatform/hello_world.mfk

@@ -3,9 +3,10 @@
 
 import stdio
 
-array hello_world = "hello world"
+array hello_world = "Hello world"
 
 void main() {
+    ensure_mixedcase()
 
 #if CBM_64 || CBM_264
     set_bg_color(green)
@@ -16,7 +17,7 @@ void main() {
 
     putstr(hello_world, hello_world.length)
     new_line()
-    putstrz("hello world again"z)
+    putstrz("Hello world again"z)
 
 #if not(CPM)
     while(true){}

include/random.mfk

@@ -0,0 +1,10 @@
+
+word rand_seed
+
+#if ARCH_6502
+import random_6502
+#elseif ARCH_I80
+import random_i80
+#else
+#warn Unsupported architecture
+#endif

include/random_6502.mfk

@@ -0,0 +1,43 @@
+
+import random
+
+#if not(ARCH_6502)
+#warn random_6502 module should be only used on 6502-compatible targets
+#endif
+
+asm byte rand() {
+    ? ldx #8
+    ? lda rand_seed+0
+__rand_loop:
+    asl
+    ? rol rand_seed+1
+    bcc __no_eor
+    eor #$2D
+__no_eor:
+    dex
+    bne __rand_loop
+    ? sta rand_seed+0
+    ? rts
+}
+
+
+#if CBM_64
+
+void init_rand_seed() {
+    poke($D40E, $ff)
+    poke($D40F, $ff)
+    poke($D412, $80)
+    while vic_raster != $70 {}
+    rand_seed.hi = peek($D41B)
+    while vic_raster != $40 {}
+    rand_seed.lo = peek($D41B)
+}
+
+#else
+
+inline void init_rand_seed() {
+    // TODO: find a better source of randomness
+    rand_seed = 1
+}
+
+#endif

include/random_i80.mfk

@@ -0,0 +1,47 @@
+
+import random
+
+#if not(ARCH_I80)
+#warn stdlib_i80 module should be only used on Intel 8080-like targets
+#endif
+
+#pragma zilog_syntax
+
+asm byte rand() {
+    ld b,8
+    ld hl,(rand_seed)
+__rand_loop:
+    add hl,hl
+    ? jp nc, __no_eor
+    ld a,l
+    xor $2D
+    ld l,a
+__no_eor:
+#if CPUFEATURE_Z80
+    djnz __rand_loop
+#else
+    dec b
+    ? jp nz, __rand_loop
+#endif
+    ld (rand_seed),hl
+    ? ret
+}
+
+#if CPUFEATURE_Z80
+
+inline asm void init_rand_seed() {
+    ld a,r
+    ld (rand_seed), a
+    ld a,r
+    ld (rand_seed+1), a
+    ? ret
+}
+
+#else
+
+inline void init_rand_seed() {
+    // TODO: find a better source of randomness
+    rand_seed = 1
+}
+
+#endif

include/stdio.mfk

@@ -59,3 +59,18 @@ void putword(word w) {
         putchar('0')
     }
 }
+
+#if CBM_PET
+inline asm void ensure_mixedcase() {
+    ? lda #14
+    ! sta 59468
+    ? rts
+}
+#elseif CBM
+inline void ensure_mixedcase() {
+    putchar(14)
+}
+#else
+inline void ensure_mixedcase() {
+}
+#endif