Add zero-page load/store LDZ/STZ ops

2 files changed, 131 insertions, 34 deletions

diff --git a/src/main.c b/src/main.c
index b1ad7cb..5f20029 100644
--- a/src/main.c
+++ b/src/main.c
@@ -116,16 +116,31 @@ init_uxn() {
         // 0xa0, 0x0f, 0x88, 0x1e, // -> ( 87 )
         // 0xa0, 0xf0, 0x08, 0x1e, // -> ( f8 )
         // 0xa0, 0xf0, 0x0f, 0xa0, 0xaa, 0xaa, 0x3e, // -> ( 5a a5 )
-        // SFT.
-        0xa0, 0x34, 0x10, 0x1f, // -> ( 68 )
-        0xa0, 0x34, 0x01, 0x1f, // -> ( 1a )
-        0xa0, 0x34, 0x33, 0x1f, // -> ( 30 )
-        0xa0, 0x12, 0x48, 0x80, 0x34, 0x3f, // -> ( 09 20 )
-
+        // // SFT.
+        // 0xa0, 0x34, 0x10, 0x1f, // -> ( 68 )
+        // 0xa0, 0x34, 0x01, 0x1f, // -> ( 1a )
+        // 0xa0, 0x34, 0x33, 0x1f, // -> ( 30 )
+        // 0xa0, 0x12, 0x48, 0x80, 0x34, 0x3f, // -> ( 09 20 )
+        // STZ / LDZ.
+        0xa0, 0x34, 0x00, 0x11,             // STZ   (u8*)uxn_ram[1] = 0x34
+        0xa0, 0xaa, 0xbb, 0x80, 0x01, 0x31, // STZ2 (u16*)uxn_ram[1] = 0x34
+        0x80, 0x00, 0x10,                   // LDZ  -> ( 34 )
+        0x80, 0x01, 0x30,                   // LDZ2 -> ( aa bb )
     };
     memcpy(uxn_ram + PAGE_PROGRAM, uxn_rom, sizeof(uxn_rom));
 }
 
+// TODO:
+//  - Division
+//  - DEI/DEO
+//  - Relative load/store
+//  - Absolute load/store
+//  - Jump instructions (JMP/JCN/JCI/JMI/JSI/JSR)
+//  - OPr modes
+//  - OPk modes
+//  - OPrk modes
+//
+
 int
 main(void) {
     // Adjust system wait times.
@@ -167,23 +182,48 @@ main(void) {
         io_ports[i] = 0;
     }
 
-    txt_printf("ROM");
+    // txt_printf("ROM");
+    // for (size_t i = 0; i < 64; i++) {
+    //     if (i % 8 == 0) {
+    //         txt_printf("\n");
+    //     }
+    //     txt_printf("%02x ", uxn_ram[i + PAGE_PROGRAM]);
+    // }
+    // txt_printf("\n\n");
+
+    uxn_eval_asm(PAGE_PROGRAM);
+    txt_printf("WST (");
+    txt_printf("SIZE: %d)", wst_ptr - (uintptr_t)wst);
     for (size_t i = 0; i < 64; i++) {
         if (i % 8 == 0) {
             txt_printf("\n");
         }
-        txt_printf("%02x ", uxn_ram[i + PAGE_PROGRAM]);
+        if (i >= (wst_ptr - (uintptr_t)wst)) {
+            txt_printf("%02x ", 0);
+        } else {
+            txt_printf("%02x ", wst[i]);
+        }
     }
+    // txt_printf("\n\n");
+    // txt_printf("RST (");
+    // txt_printf("SIZE: %d)", rst_ptr - (uintptr_t)rst);
+    // for (size_t i = 0; i < 64; i++) {
+    //     if (i % 8 == 0) {
+    //         txt_printf("\n");
+    //     }
+    //     if (i >= (rst_ptr - (uintptr_t)rst)) {
+    //         txt_printf("%02x ", 0);
+    //     } else {
+    //         txt_printf("%02x ", rst[i]);
+    //     }
+    // }
     txt_printf("\n\n");
-
-    uxn_eval_asm(PAGE_PROGRAM);
-    txt_printf("STACK (");
-    txt_printf("PTR: %d)", wst_ptr - (uintptr_t)wst);
+    txt_printf("RAM (ZP)\n");
     for (size_t i = 0; i < 64; i++) {
         if (i % 8 == 0) {
             txt_printf("\n");
         }
-        txt_printf("%02x ", wst[i]);
+        txt_printf("%02x ", uxn_ram[i]);
     }
 
     uintptr_t stack_size = wst_ptr - (uintptr_t)wst;
diff --git a/src/uxn-core.s b/src/uxn-core.s
index 9288ccf..ed860d6 100644
--- a/src/uxn-core.s
+++ b/src/uxn-core.s
@@ -23,17 +23,19 @@ io_ports: .space 256
 @ UXN evaluation function.
 @
 @   r0: PC pointer (argument is offset from RAM).
-@   r1: Stack pointer (wst/rst).
-@   r2: Ram ptr.
-@   r3-r7: Scratch registers.
+@   r1: Stack pointer (wst).
+@   r2: Stack pointer (rst).
+@   r7: Ram ptr.
+@   r3-r6: Scratch registers.
 @
 .global uxn_eval_asm
 uxn_eval_asm:
     @ Initialization.
     push    {r4-r7}
     ldr     r1, wst_ptr
-    ldr     r2, =uxn_ram
-    add     r0, r0, r2
+    ldr     r2, rst_ptr
+    ldr     r7, =uxn_ram
+    add     r0, r0, r7
 
 uxn_decode:
     ldrb    r3, [r0], #1 @ current OP value / table index
@@ -44,9 +46,11 @@ uxn_decode:
     bx      r4                   @ op_table[idx * 4]()
 
 uxn_ret:
-    @ Update stack pointer and return.
+    @ Update stack pointers and return.
     adr     r0, wst_ptr
     str     r1, [r0]
+    adr     r0, rst_ptr
+    str     r2, [r0]
     pop     {r4-r7}
     bx      lr
 
@@ -54,6 +58,10 @@ uxn_ret:
 @ Macros.
 @
 
+.macro next a
+    ldrb    \a, [r0], #1
+.endm
+
 .macro wpop8 a
     ldrb    \a, [r1, #-1]!
 .endm
@@ -78,6 +86,31 @@ uxn_ret:
     ldrb    \a, [r1, \b]
 .endm
 
+.macro rpush8 a
+    strb    \a, [r2], #1
+.endm
+
+.macro rpush16 a
+    strb    \a, [r2, #1]
+    lsr     \a, #8
+    strb    \a, [r2], #2
+.endm
+
+.macro zsave8 val, off
+    strb    \val, [r7, \off]
+.endm
+
+.macro zsave16 val, off
+    add     \off, r7
+    strb    \val, [\off, #1]
+    lsr     \val, #8
+    strb    \val, [\off]
+.endm
+
+.macro zload8 dst, off
+    ldrb    \dst, [r7, \off]
+.endm
+
 @ OP table
 op_table:
     .word brk   @ 0x00
@@ -96,7 +129,7 @@ op_table:
     .word jcn   @ 0x0d
     .word jsr   @ 0x0e
     .word sth   @ 0x0f
-    .word ldz   @ 0x00
+    .word ldz   @ 0x10
     .word stz   @ 0x11
     .word ldr   @ 0x12
     .word str   @ 0x13
@@ -209,7 +242,7 @@ op_table:
     .word brk   @ 0x7d
     .word brk   @ 0x7e
     .word brk   @ 0x7f
-    .word litr  @ 0x80
+    .word lit   @ 0x80
     .word brk   @ 0x81
     .word brk   @ 0x82
     .word brk   @ 0x83
@@ -241,7 +274,7 @@ op_table:
     .word brk   @ 0x9d
     .word brk   @ 0x9e
     .word brk   @ 0x9f
-    .word lit2r @ 0xa0
+    .word lit2  @ 0xa0
     .word brk   @ 0xa1
     .word brk   @ 0xa2
     .word brk   @ 0xa3
@@ -331,10 +364,10 @@ op_table:
     .word brk   @ 0xf7
     .word brk   @ 0xf8
 @ TODO: Can we mask this instead of having empty space?
-    .word lit2r @ 0xf9
-    .word litr  @ 0xfa
-    .word lit2r @ 0xfb
-    .word litr  @ 0xfc
+    .word lit2  @ 0xf9
+    .word lit   @ 0xfa
+    .word lit2  @ 0xfb
+    .word lit   @ 0xfc
     .word jsi   @ 0xfd
     .word jmi   @ 0xfe
     .word jci   @ 0xff
@@ -347,24 +380,29 @@ brk:
     b       uxn_ret
 
 jci:
+    wpop8   r3
+    cmp     r3, #0
+    @ TODO: What to do here? Reference not fully clear.
     b       uxn_decode
 
 jmi:
+    @ TODO: What to do here? Reference not fully clear.
     b       uxn_decode
 
 jsi:
+    @ TODO: What to do here? Reference not fully clear.
     b       uxn_decode
 
-litr:
-    ldrb    r3, [r0], #1
-    strb    r3, [r1], #1
+lit:
+    next    r3
+    wpush8  r3
     b       uxn_decode
 
-lit2r:
-    ldrb    r3, [r0], #1
-    ldrb    r4, [r0], #1
-    strb    r3, [r1], #1
-    strb    r4, [r1], #1
+lit2:
+    next    r3
+    next    r4
+    wpush8  r3
+    wpush8  r4
     b       uxn_decode
 
 inc:
@@ -544,21 +582,40 @@ jsr2:
     b       uxn_decode
 
 sth:
+    wpop8   r3
+    rpush8  r3
     b       uxn_decode
 
 sth2:
+    wpop16  r3, r5
+    rpush16 r3
     b       uxn_decode
 
 ldz:
+    wpop8   r3
+    zload8  r4, r3
+    wpush8  r4
     b       uxn_decode
 
 ldz2:
+    wpop8   r3
+    zload8  r4, r3
+    wpush8  r4
+    add     r3, #1
+    zload8  r4, r3
+    wpush8  r4
     b       uxn_decode
 
 stz:
+    wpop8   r3
+    wpop8   r4
+    zsave8  r4, r3
     b       uxn_decode
 
 stz2:
+    wpop8   r3
+    wpop16  r4, r5
+    zsave16 r4, r3
     b       uxn_decode
 
 ldr: