corrected MIN and MAX

macros/README.md

@@ -79,7 +79,13 @@ These resolve to: `.cfi_startproc` and `.cfi_endproc` respectively.
 
 ### MIN and MAX
 
-Handy more readable macros for determining minima and maxima.
+Handy more readable macros for determining minima and maxima. Note that
+the macro performs a `cmp` which subtracts `src_b` from `src_a`
+(discarding the results) in order to set the flags to be interpreted by
+the following `csel`.
+
+Thank you to u/TNorthover for nudge to add the cmp directly into the
+macro.
 
 Signature:
 

macros/double.S

@@ -1,3 +1,6 @@
+/*  A test program.
+*/
+
 #include "apple-linux-convergence.S"
 
         .text
@@ -23,7 +26,6 @@ MAIN
         END_PROC
 
 dbl:    .double     -0.55
-flt:    .float      0.125
-fmt:    .asciz      "%f\n"
+fmt:    .asciz      "Should print -0.550000: %f\n"
 
         .end

macros/float.S

@@ -1,3 +1,5 @@
+/*  A test program.
+*/
 #include "apple-linux-convergence.S"
 
         .text
@@ -24,6 +26,6 @@ MAIN
         END_PROC
 
 flt:    .float      0.125
-fmt:    .asciz      "%f\n"
+fmt:    .asciz      "Should print 0.125000: %f\n"
 
         .end

macros/minmax.S

@@ -0,0 +1,96 @@
+/*  A test program. Tests MIN and MAX
+*/
+#include "apple-linux-convergence.S"
+
+        .text
+        .align      2
+        GLABEL      main
+
+MAIN
+        START_PROC
+        PUSH_P      x29, x30
+        PUSH_P      x20, x21
+        mov         x29, sp
+
+        // Generate two numbers to compare.
+
+        mov         x0, xzr
+        CRT         time            // time(nullptr)
+        CRT         srand
+
+        CRT         rand
+        and         x20, x0, 0xFF
+
+        CRT         rand
+        and         x21, x0, 0xFF
+
+        bl          PrintLegend
+        bl          DoMin
+        bl          DoMax
+
+        POP_P       x20, x21
+        POP_P       x29, x30
+        mov         w0, wzr
+        ret
+        END_PROC
+
+DoMin:
+        START_PROC
+        PUSH_P      x29, x30
+        mov         x29, sp
+        LLD_ADDR    x0, fmtls
+        MIN         x20, x21, x1
+#if defined(__APPLE__)
+        PUSH_R      x1
+        CRT         printf
+        add         sp, sp, 16
+#else
+        CRT         printf
+#endif
+        POP_P       x29, x30
+        ret
+        END_PROC
+
+DoMax:
+        START_PROC
+        PUSH_P      x29, x30
+        mov         x29, sp
+        LLD_ADDR    x0, fmtgt
+        MAX         x20, x21, x1
+#if defined(__APPLE__)
+        PUSH_R      x1
+        CRT         printf
+        add         sp, sp, 16
+#else
+        CRT         printf
+#endif
+        POP_P       x29, x30
+        ret
+        END_PROC
+
+PrintLegend:
+        START_PROC
+        PUSH_P      x29, x30
+        mov         x29, sp
+        LLD_ADDR    x0, fmt
+#if defined(__APPLE__)
+        PUSH_P      x20, x21
+        CRT         printf
+        add         sp, sp, 16
+#else
+        mov         x1, x20
+        mov         x2, x21
+        CRT         printf
+#endif
+        POP_P       x29, x30
+        ret
+        END_PROC
+
+        .p2align    2
+fmt:    .asciz      "Values to compare: %d and %d\n"
+        .p2align    2
+fmtgt:  .asciz      "Greater value is: %d\n"
+        .p2align    2
+fmtls:  .asciz      "Lesser value is:  %d\n"
+
+        .end

more/apple_silicon/apple-linux-convergence.S

@@ -119,10 +119,28 @@ main:
         ldr     \a, [sp], 16
 .endm
 
-.macro  MIN     src_a, src_b, dest
-        csel    \dest, \src_a, \src_b, GT
-.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  MAX     src_a, src_b, dest
+.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

python/apple-linux-convergence.S

@@ -119,10 +119,28 @@ main:
         ldr     \a, [sp], 16
 .endm
 
-.macro  MIN     src_a, src_b, dest
-        csel    \dest, \src_a, \src_b, GT
-.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  MAX     src_a, src_b, dest
+.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

section_1/hello_world/apple-linux-convergence.S

@@ -119,10 +119,28 @@ main:
         ldr     \a, [sp], 16
 .endm
 
-.macro  MIN     src_a, src_b, dest
-        csel    \dest, \src_a, \src_b, GT
-.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  MAX     src_a, src_b, dest
+.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

section_1/regs/quinn.S

@@ -0,0 +1,27 @@
+		.p2align	2
+		.text
+		.global		main
+
+main:		stp		x29, x30, [sp, -16]!
+		str		x20, [sp, -16]!
+		mov		x29, sp
+		mov		x20, xzr
+
+1:		cmp		x20, 10
+		beq		2f
+		ldr		x0, =fmt
+		mov		x1, x20
+		bl		printf
+		add		x20, x20, 1
+		b 		1b
+
+2:		ldr		x20, [sp], 16
+		ldp		x29, x30, [sp], 16
+		mov		w0, wzr
+		ret
+
+		.data
+
+fmt:		.asciz		"Number: %d\n"
+		.end
+

section_2/float/apple-linux-convergence.S

@@ -119,10 +119,28 @@ main:
         ldr     \a, [sp], 16
 .endm
 
-.macro  MIN     src_a, src_b, dest
-        csel    \dest, \src_a, \src_b, GT
-.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  MAX     src_a, src_b, dest
+.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