Merge branch 'main' of https://github.com/pkivolowitz/asm_book

README.md

@@ -324,6 +324,7 @@ contained therein are applicable to all languages.
 | 6 | [Calling Assembly Language From Python](./python/) | [Link](./python/README.pdf) |
 | 7 | [Atomic Operations](./more/atomics/README.md) | [Link](./more/atomics/README.pdf) |
 | 8 | [Jump Tables](./more/jump_tables/README.md) | [Link](./more/jump_tables/README.pdf) |
+| 9 | [argv](./more/argv_example/jess1.S) | ASM CODE |
 | - | [Debugging Lecture](./debugging/Discourses%20and%20Dialogs%20on%20Debugging.pptx) | PPTX |
 
 ## Macro Suite

more/argv_example/apple-linux-convergence.S

@@ -0,0 +1,156 @@
+/*  Macros to permit the "same" assembly language to build on ARM64
+    Linux systems as well as Apple Silicon systems.
+
+    See the fuller documentation at:
+    https://github.com/pkivolowitz/asm_book/blob/main/macros/README.md
+
+    Perry Kivolowitz
+    A Gentle Introduction to Assembly Language
+*/
+
+.macro  GLD_PTR     xreg, label
+#if defined(__APPLE__)
+        adrp	    \xreg, _\label@GOTPAGE
+        ldr	        \xreg, [\xreg, _\label@GOTPAGEOFF]
+#else
+        ldr         \xreg, =\label
+        ldr         \xreg, [\xreg]
+#endif
+.endm
+
+.macro  GLD_ADDR    xreg, label     // Get a global address
+#if defined(__APPLE__)
+        adrp	    \xreg, _\label@GOTPAGE
+        add         \xreg, \xreg, _\label@GOTPAGEOFF
+#else
+        ldr         \xreg, =\label
+#endif
+.endm
+
+.macro  LLD_ADDR xreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+#else
+        ldr         \xreg, =\label
+#endif
+.endm
+
+.macro  LLD_DBL xreg, dreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+        ldur    \dreg, [\xreg]
+//      fmov    \dreg, \xreg
+#else
+        ldr     \xreg, =\label
+        ldur    \dreg, [\xreg]
+#endif
+.endm
+
+.macro  LLD_FLT xreg, sreg, label
+#if defined(__APPLE__)
+        adrp    \xreg, \label@PAGE
+        add     \xreg, \xreg, \label@PAGEOFF
+        ldur    \sreg, [\xreg]
+#else
+        ldr     \xreg, =\label
+        ldur    \sreg, [\xreg]
+#endif
+.endm
+
+.macro GLABEL label
+#if defined(__APPLE__)
+        .global _\label
+#else
+        .global \label
+#endif
+.endm
+
+.macro MAIN
+#if defined(__APPLE__)
+_main:
+#else
+main:
+#endif
+.endm
+
+/*  Fetching the address of the externally defined errno is quite
+    different on Apple and Linux. This macro leaves the address of
+    errno in x0.
+*/
+.macro  ERRNO_ADDR
+#if defined(__APPLE__)
+        bl      ___error
+#else
+        bl      __errno_location
+#endif
+.endm
+
+.macro  CRT label
+#if defined(__APPLE__)
+        bl  _\label
+#else
+        bl  \label
+#endif
+.endm
+
+.macro  START_PROC          // after starting label
+        .cfi_startproc
+.endm
+
+.macro  END_PROC            // after the return
+        .cfi_endproc
+.endm
+
+.macro  PUSH_P  a, b 
+        stp     \a, \b, [sp, -16]!
+.endm
+
+.macro  PUSH_R  a 
+        str     \a, [sp, -16]!
+.endm
+
+.macro  POP_P   a, b 
+        ldp     \a, \b, [sp], 16
+.endm
+
+.macro  POP_R   a 
+        ldr     \a, [sp], 16
+.endm
+
+/*  The smaller of src_a and src_b is put into dest. A cmp instruction
+    or other instruction that sets the flags must be performed first.
+    This macro makes it easy to remember which register does what in the
+    csel.
+    
+    Thank you to u/TNorthover for nudge to add the cmp.
+*/
+
+.macro  MIN     src_a, src_b, dest
+        cmp     \src_a, \src_b
+        csel    \dest, \src_a, \src_b, LT
+.endm
+
+/*  The larger of src_a and src_b is put into dest. A cmp instruction
+    or other instruction that sets the flags must be performed first.
+    This macro makes it easy to remember which register does what in the
+    csel.
+
+    Thank you to u/TNorthover for nudge to add the cmp.
+*/
+
+.macro  MAX     src_a, src_b, dest
+        cmp     \src_a, \src_b
+        csel    \dest, \src_a, \src_b, GT
+.endm
+
+.macro  AASCIZ      label, string
+        .p2align    2
+\label: .asciz      "\string"
+.endm
+
+.macro  MOD         src_a, src_b, dest, scratch
+        sdiv        \scratch, \src_a, \src_b
+        msub        \dest, \scratch, \src_b, \src_a
+.endm

more/argv_example/jess1.S

@@ -0,0 +1,111 @@
+#include "apple-linux-convergence.S"
+
+        .p2align    2
+        .text
+        GLABEL      main
+
+/*  This program will get a string followed by a double followed by an
+    integer from the command line demonstrating how each of these types
+    can be retrieved.
+
+    Example:
+    ./a.out test 29.3 29
+*/
+
+MAIN
+        PUSH_P      x29, x30
+        mov         x29, sp
+
+        // Check argc to see if it is 4. This is not the only way to
+        // validate command line arguments but it is an easy way.
+        cmp         w0, 4
+        bne         99f         // take branch if argc isn't "right".
+
+        // Skip past argv[0]
+        add         x1, x1, 8
+
+        // Fetch argv[1] as a string.
+        // x1 is a pointer to a pointer to chars (i.e. the string).
+        // Being a pointer to a pointer, it must be dereferenced to
+        // make a pointer.
+        ldr         x0, [x1]    // dereference
+        // Now x0 contains a pointer to the command line argument.
+        // Print the string (as a string). But doing this causes a
+        // function call which will destroy x1. So, save x1 temporarily.
+        // This could be avoided if x1 were moved to a backed up x
+        // register (e.g. x20).
+        PUSH_R      x1
+        CRT         puts    // ptr is in x0 where puts() needs it.
+        POP_R       x1
+
+        // Advance x1 once again to get to argv[2] which can be done
+        // in the same instruction as dereferencing it use a
+        // preincrement.
+        ldr         x0, [x1, 8]!    // dereference
+
+        // Now the string version of argv[2] is now pointed to by x0.
+        // This is exactly where atof would want it. We need atof
+        // because it turns strings into numbers. BUT, same as before,
+        // calling a function would destroy x1 so let's do the same
+        // trick of backing up x1 on the stack and then restoring after
+        // the function call.
+        PUSH_R      x1
+        CRT         atof    // ptr is in x0 where atof() needs it.
+        POP_R       x1
+        // The string value will be converted to a double left in d0.
+        // d0 is also a scratch register so for our next call to atoi,
+        // d0 will have to be preserved on the stack - alternatively,
+        // we could have used a high d register backed up and restored
+        // at the start and ending of main().
+
+        // Advance x1 once again to get to argv[3] which can be done
+        // in the same instruction as dereferencing it use a
+        // preincrement.
+        ldr         x0, [x1, 8]!  // dereference
+
+        // Now the string version of argv[3] is now pointed to by x0.
+        // This is exactly where atoi would want it. We need atoi
+        // because it turns strings into numbers. BUT, same as before,
+        // calling a function would destroy x1 so let's do the same
+        // trick of backing up x1 on the stack and then restoring after
+        // the function call. We must also do the same for d0. Actually,
+        // we won't need argv after this so we will skip backing up x1.
+
+        PUSH_R      d0
+        CRT         atoi    // ptr is in x0 where atof() needs it.
+        POP_R       d0
+        // d0 now contains the double.
+        // x0 now contains the integer.
+        // x0 must be copied to x1 because x0 must be a pointer to fmt
+        // for printf to work.
+        mov         x1, x0
+        LLD_ADDR    x0, fmt
+#if defined(__APPLE__)
+        sub         sp, sp, 16
+        str         x1, [sp, 8]
+        str         d0, [sp]
+        CRT         printf
+        add         sp, sp, 16 
+#else
+        bl          printf
+#endif
+
+99:     POP_P       x29, x30
+        mov         w0, wzr
+        ret
+
+/* What did we learn?
+    * x1 has argv when main begins.
+    * pointers to the arguments are the contents of argv NOT
+    the actual values. Therefore, x1, which is a pointer (to a pointer),
+    must be dereferenced to get to the actual pointer. In the code,
+    there are three lines with the comment "// dereference".
+    * all command line arguments are c-strings. If that's not what you
+    want, they must be converted - see the code for atoi and atof for
+    examples.
+*/
+        .data
+
+fmt:    .asciz      "double: %f integer: %d\n"
+
+        .end

projects/SINE/README.md

@@ -17,7 +17,9 @@ sin x = x - x^3/3! + x^5/5! - x^7/7! ...
 
 Notice each term flips from addition to subtraction.
 
-Notice each term is based on the odd integers starting at 1.
+Notice each term is based on the odd integers starting at 1. While the
+"1" case might look different, it is the same as all the others since
+1 is just 1 to the first power divided by 1 factorial.
 
 ## Command line
 
@@ -29,40 +31,76 @@ arguments are therefore required.
   be a double.
 
 * The number of terms to evaluate. The number of terms must lie between
-  1 and 10 inclusive.
+  1 and 10 inclusive. Note the value of 10 as an upper bound in new. It
+  was 8.
 
 ## C version
 
 To assist your efforts, [here](./c_version.c) is a version of this
-project written in C.
+project written in C. This has been updated to print nice debugging
+output which is not part of the project.
 
-## Errors to stderr
-
-Error messages must be sent to `stderr`.
-
-If you are using the convergence macros to allow your program to build
-on both Apple Silicon Mac OS and Linux, note the special casing needed
-to deal with `stderr`. If this is you, compile the C version on Mac OS
-with the `-S` compiler option to see the generated assembly language and
-search for `stderr`.
+This C version also demonstrates a different way of calculating the
+toggle. This version flips the sign of the toggle by multiplying by -1.
+The previous version used odd and even values of the term.
 
 ## Sample executions
 
 ```text
-SINE % ./a.out 0 8
-The sine of 0.00 degrees is 0.000000 in radians.
-SINE % ./a.out 90 8
-The sine of 90.00 degrees is 1.000000 in radians.
-SINE % ./a.out 180 8
-The sine of 180.00 degrees is -0.000001 in radians.
-SINE % ./a.out 180 82
+pk_taylor_series > gcc main.S -o a
+pk_taylor_series > ./a 0 10
+The sine of 0.00 degrees is 0.00000000.
+pk_taylor_series > ./a 30 10
+The sine of 30.00 degrees is 0.50000000.
+pk_taylor_series > ./a 45 10
+The sine of 45.00 degrees is 0.70710678.
+pk_taylor_series > ./a 90 10
+The sine of 90.00 degrees is 1.00000000.
+pk_taylor_series > ./a 180 10
+The sine of 180.00 degrees is -0.00000000.
+pk_taylor_series > ./a 360 10
+The sine of 360.00 degrees is -0.00104818.
+pk_taylor_series > ./a 360 100
 Number of terms is out of range.
-SINE % ./a.out 180 -10
+pk_taylor_series > ./a 360 -1
 Number of terms is out of range.
-SINE % echo $?
-1
+pk_taylor_series > 
 ```
 
+## Floating point instructions I used
+
+These are the floating point instructions I used in my implementation.
+
+* fmov
+
+* scvtf
+
+* fmul
+
+* fdiv
+
+* fadd
+
+## How I broke up the program
+
+I have functions named:
+
+* main
+
+* HandleOptions
+
+* Factorial
+
+* IntegerPower - x to the nth power
+
+* ComputeSine - The main calculation
+
+* PrintAnswer
+
+* ConvertTheta - Wrap D2R
+
+* D2R - Degrees to radians
+
 ## CSC3510
 
 The following applies to Carthage College CSC3510 students.
@@ -74,4 +112,3 @@ Work is to be done solo.
 ### What to hand in
 
 Just the .S file. **Your name must be at the top of the file.**
-

projects/SINE/c_version.c

@@ -1,13 +1,14 @@
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 
-double pi = 3.14159265359;
+double pi = 3.14159265358979323846;
 
 double D2R(double d) {
     return d * pi / 180.0;
 }
 
-long Factorial(int n) {
+double Factorial(int n) {
     long retval = 1;
 
     if (n > 0) {
@@ -15,7 +16,7 @@ long Factorial(int n) {
             retval = retval * n--;
         }
     }
-    return retval;
+    return (double) retval;
 }
 
 double IntegerPower(double b, int e) {
@@ -48,20 +49,20 @@ int main(int argc, char ** argv) {
 
     double r_angle = D2R(angle);
 
+    double toggle = 1.0;
     for (int term = 0, base = 1; term < terms; term++, base += 2) {
-        double toggle = (term & 1) ? -1.0 : 1.0;
-
+		if (toggle > 0) {
+			printf("%+03.8e + %+03.8e / %+03.8e [term %2d is %+03.8e]\n", sin, IntegerPower(r_angle, base),
+				   Factorial(base), term + 1, toggle * IntegerPower(r_angle, base) / Factorial(base));
+		} else {
+			printf("%+03.8e - %+03.8e / %+03.8e [term %2d is %+03.8e]\n", sin, IntegerPower(r_angle, base),
+				   Factorial(base), term + 1, toggle * IntegerPower(r_angle, base) / Factorial(base));
+		}
 		sin += toggle *
 			   IntegerPower(r_angle, base) / Factorial(base);
-        /*
-		if (toggle > 0) {
-			printf("adding      %d p/b intermediate: %f\n", base, sin);
-		} else {
-			printf("subtracting %d p/b intermediate: %f\n", base, sin);
-		}
-        */
+        toggle = toggle * -1;
 	}
-	printf("The sine of %.2f degrees is %f in radians.\n", angle, sin);
+	printf("The sine of %0.4f degrees is %0.10f.\n", angle, sin);
 
     return 0;
 }