Update README.md

README.md

@@ -4,3 +4,89 @@ This debugger hosts sim65 cpu engine and emulates the sim65 environment.
 It understands the PV hooks of sim65
 
 It understands the cc65 parameter stack
+
+# features
+- load VICE symbol files
+- breakpoints
+- next / step
+- watch points to trap reads or write to memory locations
+- smart stack display
+- WIP - stack mismatch detection
+- WIP - reading memory not written to
+- TODO - cc65 param stack awareness
+
+# building
+Its written in rust so you need rust installed to build
+
+You need a c compiler somewhere , cargo cc / build.rs will find it
+
+then just `cargo build`
+
+# use
+simple demo of use
+```
+PS C:\work\db65> cat filetest.c
+#include <stdio.h>
+int main()
+{
+    int len;
+    char buf[100];
+    FILE *foo = fopen("foo.txt", "w");
+    len = fprintf(foo, "Hello, World!");
+    printf("fd=%d len=%d\n", fileno(foo), len);
+    fclose(foo);
+
+    foo = fopen("foo.txt", "r");
+    printf("fd=%d len=%d\n", fileno(foo), len);
+    fgets(buf, 100, foo);
+    printf("hello: ");
+    fclose(foo);
+    fprintf(stderr, "hello stderr\n");
+    scanf("%s", buf);
+    printf("buf=%s\n", buf);
+}
+PS C:\work\db65> cl65 -t sim6502 filetest.c -g -Ln filetest.sym
+filetest.c:19: Warning: Control reaches end of non-void function [-Wreturn-type]
+PS C:\work\db65> C:\Users\paulm\Downloads\db65
+>> load filetest
+>> ll filetest.sym
+>> ls main
+0x0f27 .callmain
+0x0229 ._main
+>> break ._main
+>> run
+bp #1 ._main
+0229:       ldy   #$66      A=00 X=00 Y=04 SP=fd SR=no-BdiCz
+>> dis
+.__CONSTRUCTOR_TABLE__:
+0229:       ldy   #$66
+022b:       jsr   .subysp
+022e:       lda   #$A3
+0230:       ldx   #$17
+0232:       jsr   .pushax
+0235:       lda   #$B6
+0237:       ldx   #$17
+0239:       jsr   ._fopen
+023c:       jsr   .pushax
+023f:       ldy   #$01
+>>
+0241:       jsr   .ldaxysp
+0244:       jsr   .pushax
+0247:       lda   #$7F
+0249:       ldx   #$17
+024b:       jsr   .pushax
+024e:       ldy   #$04
+0250:       jsr   ._fprintf
+0253:       ldy   #$66
+0255:       jsr   .staxysp
+0258:       lda   #$8D
+>> g
+fd=3 len=13
+fd=4 len=0
+hello: hello stderr
+f
+buf=f
+exit
+>>
+
+```