cpu: Add initial bring-up and debug logic

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 129 insertions, 5 deletions

diff --git a/emux64/src/cpu/cpu_subr.c b/emux64/src/cpu/cpu_subr.c
new file mode 100644
index 0000000..a7be333
--- /dev/null
+++ b/emux64/src/cpu/cpu_subr.c
@@ -0,0 +1,90 @@
+/*
+ * Copyright (c) 2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <cpu/cpu.h>
+#include <stdio.h>
+#include <errno.h>
+
+void
+cpu_dump(struct osmx_core *core)
+{
+    if (core == NULL) {
+        return;
+    }
+
+    /* General purpose registers */
+    for (int i = 0; i < N_GPREG; ++i) {
+        printf("X%d=0x%016llx ", i, core->xn[i]);
+        if ((i & 1) != 0)
+            printf("\n");
+    }
+
+    for (int i = 0; i < N_FLOATREG; ++i) {
+        printf("F%d=0x%016llx ", i, core->fn[i]);
+        if ((i & 1) != 0)
+            printf("\n");
+    }
+
+    /* Double precision registers */
+    for (int i = 0; i < N_DUBREG; ++i) {
+        printf("D%d=0x%016llx ", i, core->dn[i]);
+        if ((i & 1) == 0)
+            printf("\n");
+    }
+
+    printf("PC=0x%016llx\n", core->pc);
+}
+
+int
+cpu_reset(struct osmx_core *core)
+{
+    if (core == NULL) {
+        return -EINVAL;
+    }
+
+    core->pc = CPU_BUA_PBASE;
+    core->xn[0] = 0;
+
+    /* Initialize float registers */
+    for (int i = 0; i < N_FLOATREG; ++i) {
+        core->fn[i] = 0;
+    }
+
+    /* Initialize double registers */
+    for (int i = 0; i < N_DUBREG; ++i) {
+        core->dn[i] = 0;
+    }
+
+    /* Initialize other gp regs */
+    for (int i = 1; i < N_GPREG; ++i) {
+        core->xn[i] = 0xFFFFFFFFFFFFFFFF;
+    }
+
+    return 0;
+}
diff --git a/emux64/src/include/cpu/cpu.h b/emux64/src/include/cpu/cpu.h
index 04b2a9f..9b045c9 100644
--- a/emux64/src/include/cpu/cpu.h
+++ b/emux64/src/include/cpu/cpu.h
@@ -38,6 +38,14 @@
 #include <stdint.h>
 #include <stddef.h>
 
+/* Bring up area physical base */
+#define CPU_BUA_PBASE 0xFFF00000
+
+/* Register type counts */
+#define N_GPREG    16
+#define N_FLOATREG 7
+#define N_DUBREG   7
+
 /*
  * Represents a single unit of execution
  *
@@ -47,9 +55,9 @@
  * @pc: Program counter
  */
 struct osmx_core {
-    uint64_t xn[16];
-    float fn[7];
-    double dn[7];
+    uint64_t xn[N_GPREG];
+    float fn[N_FLOATREG];
+    double dn[N_DUBREG];
     uintptr_t pc;
 };
 
@@ -60,7 +68,24 @@ struct osmx_core {
  * TODO: Dynamically allocate cores
  */
 struct osmx_cpu {
-    struct osmx_core[1];
+    struct osmx_core cores[1];
 };
 
+/*
+ * Bring the CPU to an initial reset state
+ *
+ * @core: Core to bring to reset state
+ *
+ * Returns zero on success
+ */
+int cpu_reset(struct osmx_core *core);
+
+/*
+ * Dump the registers to the console for debugging
+ * purposes
+ *
+ * @core: Core to dump
+ */
+void cpu_dump(struct osmx_core *core);
+
 #endif  /* !CPU_CPU_H */
diff --git a/emux64/src/main.c b/emux64/src/main.c
index a9a3a7f..cacd6b3 100644
--- a/emux64/src/main.c
+++ b/emux64/src/main.c
@@ -29,10 +29,19 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <cpu/cpu.h>
 
 int
 main(void)
 {
-    printf("Hello emux64!\n");
+    struct osmx_core core;
+    int error;
+
+    if ((error = cpu_reset(&core)) < 0) {
+        printf("error: failed to power up vcore\n");
+        return error;
+    }
+
+    cpu_dump(&core);
     return 0;
 }